Relative addressing with copy and paste is a wonderful tool. But there are times -- not many times, granted, but times nonetheless -- that we don't want the formulas to change.
| A | B | C | |
| 1 | Salespeople And Sales | ||
| 2 | |||
| 3 | Commrate | 8% | |
| 4 | |||
| 5 | Person | Gross Sales | Commission |
| 6 | Bill | $135,000 | =B6*C3 |
| 7 | Mike | $110,000 | |
| 8 | Molly | $225,000 |
So far, so good. We can see that Bill's commission is computed by multiplying the amount of sales (in cell B6) times the commission rate (up in cell C3). We've got a formula, it seems to work: let's copy the tar out of it
| A | B | C | |
| 1 | Salespeople And Sales | ||
| 2 | |||
| 3 | Commrate | 8% | |
| 4 | |||
| 5 | Person | Gross Sales | Commission |
| 6 | Bill | $135,000 | =B6*C3 |
| 7 | Mike | $110,000 | =B7*C4 |
| 8 | Molly | $225,000 | =B8*C5 |
Well...not too good. The rows changed for the person (B6,B7,B8), but look at the commission rate reference! It changed too, and the bottom two formulas don't do what we need them to do.
This is a case of the computer not being able to magically tell when we want the reference to change and when we want it to stay the same. We just need a way to tell it.