Talen 2639 till 2645 i romerska siffror
I högerkolumnen visas hur varje romersk siffra bidrar till att man hamnar vid rätt tal.
| 2639 | = | MMDCXXXIX | = | 1000 + 1000 + 500 + 100 + 10 + 10 + 10 + 10 − 1 |
| 2640 | = | MMDCXL | = | 1000 + 1000 + 500 + 100 + 50 − 10 |
| 2641 | = | MMDCXLI | = | 1000 + 1000 + 500 + 100 + 50 − 10 + 1 |
| 2642 | = | MMDCXLII | = | 1000 + 1000 + 500 + 100 + 50 − 10 + 1 + 1 |
| 2643 | = | MMDCXLIII | = | 1000 + 1000 + 500 + 100 + 50 − 10 + 1 + 1 + 1 |
| 2644 | = | MMDCXLIV | = | 1000 + 1000 + 500 + 100 + 50 − 10 + 5 − 1 |
| 2645 | = | MMDCXLV | = | 1000 + 1000 + 500 + 100 + 50 − 10 + 5 |