Talen 1625 till 1631 i romerska siffror
I högerkolumnen visas hur varje romersk siffra bidrar till att man hamnar vid rätt tal.
| 1625 | = | MDCXXV | = | 1000 + 500 + 100 + 10 + 10 + 5 |
| 1626 | = | MDCXXVI | = | 1000 + 500 + 100 + 10 + 10 + 5 + 1 |
| 1627 | = | MDCXXVII | = | 1000 + 500 + 100 + 10 + 10 + 5 + 1 + 1 |
| 1628 | = | MDCXXVIII | = | 1000 + 500 + 100 + 10 + 10 + 5 + 1 + 1 + 1 |
| 1629 | = | MDCXXIX | = | 1000 + 500 + 100 + 10 + 10 + 10 − 1 |
| 1630 | = | MDCXXX | = | 1000 + 500 + 100 + 10 + 10 + 10 |
| 1631 | = | MDCXXXI | = | 1000 + 500 + 100 + 10 + 10 + 10 + 1 |