I start by explaining that:
o The value of every cell on a worksheet is exactly one of the following: Empty, String, Double, Boolean, or Error
o Default cell alignment lets you see at a glance what's what (referencing the sheet below)
o Numbers and strings that look like numbers are not interchangeable
o Every Excel function operates on the values of cells, irrespective of whether they are literals or the results of formulas (including errors)
<TABLE style="WIDTH: 526pt; BORDER-COLLAPSE: collapse" border=0 cellSpacing=0 cellPadding=0 width=701 x:str><COLGROUP><COL style="WIDTH: 61pt; mso-width-source: userset; mso-width-alt: 3730" width=82><COL style="WIDTH: 200pt; mso-width-source: userset; mso-width-alt: 12178" width=266><COL style="WIDTH: 32pt; mso-width-source: userset; mso-width-alt: 1974" width=43><COL style="WIDTH: 34pt; mso-width-source: userset; mso-width-alt: 2048" width=45><COL style="WIDTH: 44pt; mso-width-source: userset; mso-width-alt: 2669" width=58><COL style="WIDTH: 30pt; mso-width-source: userset; mso-width-alt: 1828" width=40><COL style="WIDTH: 40pt; mso-width-source: userset; mso-width-alt: 2413" width=53><COL style="WIDTH: 33pt; mso-width-source: userset; mso-width-alt: 2011" width=44><COL style="WIDTH: 26pt; mso-width-source: userset; mso-width-alt: 1609" span=2 width=35><TBODY><TR style="HEIGHT: 12pt" height=16><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BACKGROUND-COLOR: #f3f3f3; WIDTH: 61pt; HEIGHT: 12pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 height=16 width=82>Cell</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 200pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=266>Remark</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 32pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=43 x:str="'=""?">=""?</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 34pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=45>IsBlank?</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 44pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=58>IsNumber?</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 30pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=40>IsText?</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 40pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=53>IsLogical?</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 33pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=44>IsError?</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 26pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=35>IsErr?</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext; BACKGROUND-COLOR: #f3f3f3; WIDTH: 26pt; BORDER-TOP: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid" class=xl30 width=35>IsNA?</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21></TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This cell is Empty</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla='=A2=""' x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISBLANK(A2)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNUMBER(A2)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISTEXT(A2)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A2)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A2)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A2)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A2)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21 x:str="" x:fmla='=IF(1=0, "Wow!", "")'></TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This cell has a formula that returns a null string</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla='=A3=""' x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISBLANK(A3)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNUMBER(A3)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISTEXT(A3)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A3)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A3)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A3)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A3)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21>Bob</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This is a string</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A4=""' x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A4)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNUMBER(A4)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISTEXT(A4)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A4)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A4)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A4)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A4)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21 x:fmla='=TEXT(TODAY(), "m/d/yyyy")'>8/16/2011</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This is a string that looks like a date</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A5=""' x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A5)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISNUMBER(A5)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISTEXT(A5)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A5)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A5)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A5)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A5)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21 x:fmla='=TEXT(12345, "0")'>12345</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This is a string that looks like a number</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A6=""' x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A6)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISNUMBER(A6)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISTEXT(A6)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A6)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A6)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A6)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A6)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21 x:fmla="=COMPLEX(1, 2)">1+2i</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This is a string that looks like a complex number</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A7=""' x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A7)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISNUMBER(A7)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISTEXT(A7)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A7)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A7)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A7)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A7)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21 x:fmla="=IMPOWER(A7, 2)">-3+4i</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< That's the complex number above squared</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A8=""' x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A8)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISNUMBER(A8)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISTEXT(A8)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A8)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A8)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A8)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A8)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21 align=middle x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This is a Boolean</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A9=""' x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A9)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNUMBER(A9)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISTEXT(A9)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISLOGICAL(A9)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A9)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A9)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A9)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21 align=middle x:fmla="=1/0" x:err="#DIV/0!">#DIV/0!</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This is an error</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A10=""' x:err="#DIV/0!">#DIV/0!</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A10)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNUMBER(A10)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISTEXT(A10)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A10)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISERROR(A10)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISERR(A10)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A10)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl31 height=21 align=middle x:err="#N/A">#N/A</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< So is this</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A11=""' x:err="#N/A">#N/A</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A11)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNUMBER(A11)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISTEXT(A11)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A11)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISERROR(A11)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ffff99; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl39 align=middle x:fmla="=ISERR(A11)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISNA(A11)" x:bool="TRUE">TRUE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl34 height=21 align=right x:fmla="=TODAY()" x:num="40771">08/16/2011</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl32><< This is a serial date (which is a number)</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla='=A12=""' x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISBLANK(A12)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl38 align=middle x:fmla="=ISNUMBER(A12)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISTEXT(A12)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A12)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERROR(A12)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISERR(A12)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISNA(A12)" x:bool="FALSE">FALSE</TD></TR><TR style="HEIGHT: 16.05pt; mso-height-source: userset" height=21><TD style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: windowtext 1pt solid; BACKGROUND-COLOR: white; HEIGHT: 16.05pt; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl35 height=21 align=right x:num>12345</TD><TD style="BORDER-BOTTOM: windowtext 1pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #909090; BORDER-TOP: windowtext; BORDER-RIGHT: windowtext 1pt solid" class=xl36><< This is a plain old number</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl37 align=middle x:fmla='=A13=""' x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl37 align=middle x:fmla="=ISBLANK(A13)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #ccffcc; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl40 align=middle x:fmla="=ISNUMBER(A13)" x:bool="TRUE">TRUE</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl37 align=middle x:fmla="=ISTEXT(A13)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl33 align=middle x:fmla="=ISLOGICAL(A13)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl37 align=middle x:fmla="=ISERROR(A13)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl37 align=middle x:fmla="=ISERR(A13)" x:bool="FALSE">FALSE</TD><TD style="BORDER-BOTTOM: #ece9d8; BORDER-LEFT: #ece9d8; BACKGROUND-COLOR: #e7e7e7; BORDER-TOP: windowtext; BORDER-RIGHT: #ece9d8" class=xl37 align=middle x:fmla="=ISNA(A13)" x:bool="FALSE">FALSE</TD></TR></TBODY></TABLE>
I walk through the examples and explain the highlighted formula results at right.