What is the Roman numeral representation for the number 40?

The Roman numeral representation for the number 40 is XL. In Roman numerals, the letter X represents 10, and the letter L represents 50. When a smaller numeral appears before a larger numeral, it indicates subtraction. Therefore, placing X before L (as in XL) signifies that 10 is subtracted from 50, resulting in 40.

This understanding of basic numeral rules in the Roman numeral system clarifies why XL is the correct representation for the number 40. It shows how Roman numerals effectively combine addition and subtraction to convey different values, particularly in cases like this where a smaller numeral precedes a larger one.