Open both file A (source file) and file B (destination file, the file that looks up info from file A).
Enter a cell in file B. Type the equals sign. Click on file B to make it active. Select the Sheet containing the data you want to reference from the file B workbook. Select the cell or range of cells you want to reference. At the top of your screen in the formula bar you’ll see something like
or, for that matter, if you were in mid-formula at the time,
anyway, you can now click on the original file you were working in to make reference to other cells or ranges there, or hit return to enter the formula and return you to the sheet and workbook from which you started.
Note that Excel will have to open the source workbook A whenever you open workbook file B. If you want static (rather than dynamic) information from A and don’t want to have to have A open, copy the relevant cells in A, go to a sheet in B and Paste Special, selecting Results, which converts =!FileA:Sheet1:A1+1 to 2 (assuming A1 in Sheet 1 of File A is equal to 1) and no longer references file A at all. Now you can refer to the pasted results within file B in your file B formulas.
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