Generally speaking a calculator answer is NOT exact, because the calculator must (usually) approximate a number. For example π is exact, but 3.1415926535897932 is not no matter how many decimals you carry. When asked for exact answers do NOT use your calculator! Here are some more examples:
| Exact | Not Exact |
| 2/3 | 0.66667 |
| exp(4) | 54.59815 |
| 9sqrt(3)/2 | 7.79422 |
| 1/4 or 0.25 | - |