I would write it (as I say it) as: zero point zero four zero zero.
It could be written as four hundredths, but the trailing zeros suggest it may have been rounded to the nearest ten thousandth, so it would be four-hundred ten-thousandths.
Chat with our AI personalities
You can write 5.24 in word form as five and twenty-four hundredths
You can write 14.12 in word form as fourteen and twelve hundredths
0030.0 in word form is thirty
8,000,000 in word form is eight million.
91 in word form is ninety-one.