Is it forty five or fourty five

"Forty-five" is the correct spelling—"fourty" is a common misspelling that should be avoided. The number 40 is spelled "forty," not "fourty," and when combined with any number from one to nine, it becomes a hyphenated compound like forty-five (45), forty-one (41), or forty-nine (49). This spelling irregularity catches many people off guard because "four" contains a "u," but "forty" does not, making it one of the most frequently misspelled numbers in English.

This spelling rule applies universally across all contexts, whether you're writing checks, formal documents, addresses, or casual text. The confusion likely stems from the fact that we spell the base number as "four," leading many to assume its tens form would follow the same pattern. However, English spelling, particularly with numbers, has historical quirks that don't always follow logical patterns. Using the incorrect "fourty-five" in professional or financial documents can undermine your credibility and attention to detail. In formal writing like contracts, cheques, or legal documents, spelling errors with numbers can sometimes raise questions about the document's validity or professionalism, making it essential to remember this exception and double-check your spelling of forty and all its compound forms.