You can square a number in Excel with the power function, which is represented by the carat ^ symbol. Use the formula =N^2, where N is either a number or the cell you want to square. You can also use this formula multiple times within your worksheet.
Square a number in its own cell

Click inside a cell on your worksheet.

Type =N^2 into the cell, where N is the number you want to square. For example, to insert the square of 5 into cell A1, type =5^2 into the cell.

Press Enter to see the result.
Tip: You can also click into another cell to see the squared result.
Square a number in a different cell

Click inside a cell. Type the number that you want to square.

Select another blank cell in your worksheet. This should be outside of the cell that contains the number you want to square.

Type =N^2 into the blank cell, where N is a cell reference that contains the number value you want to square. For example, to display the square of cell A1 in cell B1, type =A1^2 into cell B1.

Press Enter to see the result.