Spelling.School · How to spell
How to spell thirty
Thirty is spelled T-H-I-R-T-Y.
What it means: The number after twenty-nine.
In a sentence: There are thirty candles on the birthday cake.
Same family: thirteen, third, thirty-one, thirty-five, thirtieth. If you can spell one, the shared part carries to the others.
Where it comes from: “Thirty” comes from Old English “þrītig,” which literally meant “three tens.” The “-ty” ending in English number words like twenty, thirty, and forty originally meant “groups of ten.”
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