Talen 1665 till 1671 i romerska siffror
I högerkolumnen visas hur varje romersk siffra bidrar till att man hamnar vid rätt tal.
| 1665 | = | MDCLXV | = | 1000 + 500 + 100 + 50 + 10 + 5 |
| 1666 | = | MDCLXVI | = | 1000 + 500 + 100 + 50 + 10 + 5 + 1 |
| 1667 | = | MDCLXVII | = | 1000 + 500 + 100 + 50 + 10 + 5 + 1 + 1 |
| 1668 | = | MDCLXVIII | = | 1000 + 500 + 100 + 50 + 10 + 5 + 1 + 1 + 1 |
| 1669 | = | MDCLXIX | = | 1000 + 500 + 100 + 50 + 10 + 10 − 1 |
| 1670 | = | MDCLXX | = | 1000 + 500 + 100 + 50 + 10 + 10 |
| 1671 | = | MDCLXXI | = | 1000 + 500 + 100 + 50 + 10 + 10 + 1 |