Thirteen or thirty? Listen for the stress
The numbers 13 to 19 end in -teen, and 30, 40, 50 and so on end in -ty. They sound alike, so English speakers separate them with stress:
| Teen | Stress | Ten | Stress |
|---|---|---|---|
| thirteen | thir-TEEN /ˌθɝˈtin/ | thirty | THIR-ty /ˈθɝti/ |
| fifteen | fif-TEEN /ˌfɪfˈtin/ | fifty | FIF-ty /ˈfɪfti/ |
| eighteen | eigh-TEEN /ˌeɪˈtin/ | eighty | EIGH-ty /ˈeɪti/ |
In American English the t in -ty often sounds like a quick d: "thirty" can sound like "thirdy". If you are not sure what you heard, ask: "One five or five zero?"
Writing numbers as words
- Hyphens: use a hyphen between the tens and the ones from 21 to 99: twenty-one, forty-five, ninety-nine.
- Hundreds: 101 is one hundred one in American English. One hundred and one is British, and many Americans say it too, but in writing checks and forms Americans leave out "and".
- No plural -s: say two hundred, five thousand, three million, not "two hundreds". The -s is used only without a number: "hundreds of people", "millions of dollars".
- Commas: English uses a comma to separate thousands and a period for decimals: 1,000,000 is one million, and 2.5 is two point five. Many other languages do the opposite.
Big numbers
English counts in thousands: thousand (1,000), million (1,000,000), billion (1,000,000,000). There is no single word for 10,000: it is ten thousand, and 100,000 is one hundred thousand.
Read a long number in groups of three: 3,452,100 is "three million, four hundred fifty-two thousand, one hundred".
Ordinal numbers
Ordinals put things in order: first, second, third. Most add -th (fourth, tenth), but the first three are irregular, and so is any number that ends in them: twenty-first, thirty-second, forty-third. Written short, they are 1st, 2nd, 3rd, 4th, 21st.
Watch the spelling changes: five → fifth, nine → ninth, twelve → twelfth, twenty → twentieth.
Ordinals are used for dates (May 3rd, said "May third"), floors (the second floor), and places in a race.
Prices, years, and phone numbers
- Prices: $4.99 is "four ninety-nine" or "four dollars and ninety-nine cents". $20 is "twenty dollars" (not "twenty dollar").
- Years: say most years in two pairs: 1995 is "nineteen ninety-five", 2024 is "twenty twenty-four". Years 2000 to 2009 are usually "two thousand", "two thousand five".
- Phone numbers: say each digit one at a time, in groups: 555-0123 is "five five five, oh one two three".
- Zero: in phone numbers, room numbers, and years it is often said oh, like the letter O (room 105, "one oh five"). In math and temperatures it is zero.
- Percent and decimals: 25% is "twenty-five percent"; 0.5 is "point five" or "zero point five".