same data from one cell copy to multiple sheets

I have 3 worksheet and I would like to have certain cell copy into a master
sheet.
So, when you enter a number into "sheet 1" in places it into "master" the
cells are not in the same exact spot. Is there a formula to make these cells
copy into mutiple sheets?

Copy Master cell onto different sheets:
Put this in the formula bar for the cell on each of the secondary sheets
that will match the master. =Sheet1!C13 with C13 being your master cell.

Use master sheet to add number value from different sheets:
The master cell should read =SUM(Sheet2!C13,Sheet3!C10) with your
secondary cells in place of C12 and C13.
Sometimes Excel requires you to put in a $ in the formula.
Hope this helps.