Задание
Какому числу равно римское число \(\displaystyle {\rm LXXXIX}\)?
Решение
| число | десятки | единицы | ||||
| \(\displaystyle {\rm LXXXIX}\) | \(\displaystyle =\) | \(\displaystyle {\rm LXXX}\) | \(\displaystyle +\) | \(\displaystyle {\rm IX}\) | ||
| \(\displaystyle 80\) | \(\displaystyle +\) | \(\displaystyle 9\) | \(\displaystyle =\) | \(\displaystyle 89\) |
Ответ: \(\displaystyle 89\).