Math formula for determining total when each row increases by one

[WLHagen]

Hey everyone! I finally have a non-Excel question, but I'm sure the answer can be solved with Excel!!!

I'm crocheting a blanket, and for each row, the number of stitches increase by one. For example:

Row 1 = 1 stitch
Row 2 = 2 stitches (3 stitches total)
Row 3 = 3 stitches (6 stitches total)
...
Row 30 = 30 stitches (??? stitches total)

I seem to remember from my feeble brain that there was a formula that could calculate the number of total stitches, given the number of rows?

Also, is there an easier way to calculate how many total stitches would be in certain rows only (simpler than 32+33+34+35 = 134)?

I'm trying to easily determine how many stitches I've made if I've done 34 rows with 297 yards of yarn. Then, if I start a new 297 yard skein on row 35, how many full rows can I get out of that skein?

Thanks in advance!

 

[Scott Huish]

Assuming starting row in A2 and ending row in B2:

=SUMPRODUCT(ROW(INDIRECT(A2&":"&B2)))

 

[J.Ty.]

Row 1 = 1 stitch
Row 2 = 2 stitches (3 stitches total)
Row 3 = 3 stitches (6 stitches total)
...
Row n = n stitches (n*(n+1)/2 stitches total)

J.Ty.

 

[WLHagen]

Scott - thanks so much - the formula worked perfectly!!!

JTy - thanks so much - I was looking for this also - something I could use when I didn't have access to Excel, and also just to remember from my youth. I tried Google'ing for it, and didn't even know how to ask the question!

Have a blessed day!!!