excel Why use references that aren’t relative?

If you think about it, you’ll realize that the only reason why you would ever need to change a reference is if you plan to copy the formula. Figure 3-1 demonstrates why this is so. The formula in
cell C3 is
=$B3*C$2

This formula calculates the area for various lengths (listed in column B) and widths (listed in row
3). After the formula is entered, you can then copy it down to C7 and across to F7. Because the
formula uses absolute references to row 2 and column B and relative references for other rows
and columns, each copied formula produces the correct result. If the formula used only relative
references, copying the formula would cause all the references to adjust and thus produce incorrect results.