The numbers 645 to 651 in roman numerals
The right column shows how each roman numeral adds up to the total.
| 645 | = | DCXLV | = | 500 + 100 + 50 − 10 + 5 |
| 646 | = | DCXLVI | = | 500 + 100 + 50 − 10 + 5 + 1 |
| 647 | = | DCXLVII | = | 500 + 100 + 50 − 10 + 5 + 1 + 1 |
| 648 | = | DCXLVIII | = | 500 + 100 + 50 − 10 + 5 + 1 + 1 + 1 |
| 649 | = | DCXLIX | = | 500 + 100 + 50 − 10 + 10 − 1 |
| 650 | = | DCL | = | 500 + 100 + 50 |
| 651 | = | DCLI | = | 500 + 100 + 50 + 1 |