Explanation
The INDIRECT function tries to evaluate text as a valid reference.
The SHEET function then returns the current index for each sheet as listed.
SHEET will report the sheet number for a cell reference, named range, or Excel Table.
List sheet index numbers
To list the index numbers of sheets in an Excel workbook, you can enter the sheet names, then use a formula based on the SHEET and INDIRECT functions. In the example shown, the formula in C5 is: =SHEET(INDIRECT(B5&"!A1"))
