400 in words

400 is written "four hundred". That spelling is the same in British and American English.

Where each word comes from

The same number, other ways

In words (US)

Four hundred

In words (UK)

Four hundred

Ordinal

400th — four hundredth

Roman numeral

CD

Digits

400

Writing it on a cheque

On a cheque the amount line reads "Four hundred and 00/100" — or "Four hundred only" in Indian and much of Commonwealth practice. The fraction or the word "only" exists to stop anyone appending digits after what you wrote. Draw a line through any space left over for the same reason.