The numbers 1915 to 1921 in roman numerals
The right column shows how each roman numeral adds up to the total.
| 1915 | = | MCMXV | = | 1000 + 1000 − 100 + 10 + 5 |
| 1916 | = | MCMXVI | = | 1000 + 1000 − 100 + 10 + 5 + 1 |
| 1917 | = | MCMXVII | = | 1000 + 1000 − 100 + 10 + 5 + 1 + 1 |
| 1918 | = | MCMXVIII | = | 1000 + 1000 − 100 + 10 + 5 + 1 + 1 + 1 |
| 1919 | = | MCMXIX | = | 1000 + 1000 − 100 + 10 + 10 − 1 |
| 1920 | = | MCMXX | = | 1000 + 1000 − 100 + 10 + 10 |
| 1921 | = | MCMXXI | = | 1000 + 1000 − 100 + 10 + 10 + 1 |