The spelling of numbers is not as regular (or logical) as you might like.
Where did the o in two go when you look at twenty?
Where did the i in thirty come from?
etc.
The number 40 is spelled forty.
because that is how it sounds
Forty is a natural number that comes after thirty-nine and before forty-one. It is represented by the numeral 40.
Forty (40) has the letters placed in alphabetical order.
forty
The number 40 is spelled forty.
The cardinal number 40 is spelled "forty" and the adjective (ordinal) 40th is "fortieth".
In American English four meaning 4 and forty meaning 40.
The number is spelled "forty" everywhere in English.
The correct spelling of the number "14" is, indeed, "fourteen." The number "40," however, is spelled "forty."
The noun form for the number 40 is spelled forty. The plural form is forties.
Forty-one Forty-two Forty-three Forty-four Forty-five Note: 4 = Four 14 = Fourteen 40 = Forty as in letter u is omitted in 40
Sometimes 40 is spelled as forty because it sounds proper. Depending on what you are trying to say, either or could look better with the sentence.
because that is how it sounds
Forty is a natural number that comes after thirty-nine and before forty-one. It is represented by the numeral 40.
The ordinal number 40th is spelled fortieth.
40 dollars is spelled out 'Forty dollars.'