Add in formulas.

Drag the Fill Handle to fill the cells quickly.

Check in each cell to see the formula.
TASK:
Create the following multiplication number grid.

The following formula entered at B2, uses absolute
referencing =$A2*B$1 , the $ before A means that this column will
always be referred to and the $ before 1 will mean that Row 1
will always be referred to. The 2 and B will be changed as you
fill in the other cells.
Fill down:

Then across:

Go through and change the numbers on the left and the top to
see the multiplications change.