Linking sheets with equations

[lezawang]

Hi
I am reading excel course outline and I read the following:

• Linking sheets with equations
• Linking files with equations

What does that mean? how to link sheet/file with an equation? Thank you so much.
Course outline is here

http://www.ctccomputertraining.com/excel2010trainingcourses2.html

 

[sheetspread]

Could be as simple as Sheet1!A2 + Sheet3!A5, or including an indirect function like:

https://www.mrexcel.com/forum/excel-questions/560924-3-month-updating-sheet.html

(similar for different files)

 

[mikerickson]

Or it could be as complicated as a dependant hyperlink.