Talen 1615 till 1621 i romerska siffror
I högerkolumnen visas hur varje romersk siffra bidrar till att man hamnar vid rätt tal.
| 1615 | = | MDCXV | = | 1000 + 500 + 100 + 10 + 5 |
| 1616 | = | MDCXVI | = | 1000 + 500 + 100 + 10 + 5 + 1 |
| 1617 | = | MDCXVII | = | 1000 + 500 + 100 + 10 + 5 + 1 + 1 |
| 1618 | = | MDCXVIII | = | 1000 + 500 + 100 + 10 + 5 + 1 + 1 + 1 |
| 1619 | = | MDCXIX | = | 1000 + 500 + 100 + 10 + 10 − 1 |
| 1620 | = | MDCXX | = | 1000 + 500 + 100 + 10 + 10 |
| 1621 | = | MDCXXI | = | 1000 + 500 + 100 + 10 + 10 + 1 |