Using Cells From Other Worksheets Inside a Formula
For larger or more complicated projects you may need to spread data around on multiple worksheets within the same project. But when the data is spread around multiple sheets, you can use it to make equations on any sheet you wish.
All you have to do is to click the desired tab when writing your formula, and then choose the relevant cells. This will insert the name of that worksheet followed by and exclamation mark (!), which tells excel to handle it as a worksheet name.
For instance, if using a monthly spreadsheet, you can denote data from the October sheet by clicking the October tab while writing the formula. This will place the word "October!" before the cell address you need in the equation. For data from other months that you want in the same equation follow the same pattern. This will tell Excel which sheets to draw information from.
Using this simple trick, you can pull values and variables from every corner of an Excel project and deposit them into the equation and cell of your choice.