Cardinal number

1. The cardinal number occurring after thirty-nine and before forty-one, represented in Roman numerals as XL and in Arabic numerals as 40. Ordinal: fortieth.

   Arabic numerals: 40

   Roman numerals: XL

   Last: thirty (30), thirty-nine (39)

   Next: forty-one (41), fifty (50)

Usage notes

• Fourty is considered incorrect. The spelling "forty" relates to some of the other numbers representing tens. Examples: twenty rather than twoty, thirty rather than threety, and fifty rather than fivety.