P update them whenever modifications are made. The most common forumula is add up a row or column of numbers. You can make a loan calculator. P Copy the answer to the yellow cell below. Or you can write your own formulas.
P Now try cut and paste to the yellow cell below.
As you change the blue numbers the green total changes. P Notice the formula did not change. This is refered to as an absolute move since the cell references did not change. It is possible to control the changing of a formula by making references absolute. P Look at the formula in the red cell left.