fourty or forty

The correct spelling is "forty" without a "u." The spelling "fourty" is a common misspelling and is considered incorrect in both British and American English. Although "four" contains the letter "u," "forty" does not. Historically, "fourty" was used in earlier English but has fallen out of use since the 18th century. The accepted and only correct form today is "forty," including in compound forms like "forty-five" or "one-hundred-forty".