Numbers in Depth: Fractions, Percentages & Big Numbers
Level B1 · Sentence Basics
Fractions, percentages, large numbers and phone numbers are all spoken in specific patterns that don't follow simple counting. You already know that cardinal numbers (one, two, three) count things and ordinal numbers (first, second, third) show order — fractions actually combine both: the numerator (the top number) is cardinal and the denominator (the bottom number) is ordinal, so 2/3 is two thirds, cardinal two + ordinal thirds. Percentages stay simple (the number plus percent, invariable), while large round numbers like hundred, thousand and million behave like ordinary nouns only when the exact quantity is vague. Phone numbers break the normal counting rules completely: they're read one digit at a time, not as a single large number.
Fraction rules:
- numerator + ordinal denominator: 1/3 = a third, 2/3 = two thirds — the denominator adds -s once the numerator is more than one (a third but two thirds, a quarter but three quarters)
- half is irregular: never "a second" for 1/2 — say half or a half; before a noun it combines directly, with no "of": half a kilo, half an hour
- other fractions need "of" before a determiner + noun: half of my friends, three quarters of the cake, but not before a bare indefinite noun (half a kilo, not half of a kilo)
- mixed numbers keep the cardinal whole number, then "and" + the fraction: one and a half hours, two and a quarter kilos
Percentages and large numbers:
- percentages are simply number + percent, always invariable: 25 percent, 100 percent — never "percents"; British English sometimes writes it as two words, per cent, while American English writes percent as one word
- hundred, thousand, million and billion stay singular with no -s straight after a specific number: three hundred people, two million dollars
- the same words take -s and "of" when the quantity is vague rather than counted: hundreds of people, millions of dollars
- British English usually adds "and" before the tens/units in a compound number: two hundred and fifty; American English often drops it: two hundred fifty
The most common mistake is forgetting to pluralize the denominator after a numerator bigger than one: three quarter and two third are both wrong — it must be three quarters and two thirds. Another frequent error is adding an -s to percent or hundred/thousand/million right after a specific number: 25 percents and three hundreds dollars are both wrong; percent never takes -s, and hundred/thousand/million only take -s when the amount is vague and followed by of (hundreds of dollars). Phone numbers cause a different mistake: reading them as one large number instead of separate digits — a number like 7392 should be seven three nine two, not seven thousand three hundred (and) ninety-two.
To pick the right form, ask what the number is describing. A piece of a whole needs a fraction: cardinal numerator + ordinal denominator, pluralized only when the numerator is above one, with half behaving irregularly. A share out of a hundred needs percent, which never changes form. An exact quantity next to a specific number stays singular (three hundred, two million), while a rough, uncounted quantity takes -s plus of (hundreds of, millions of). And a string of digits meant to be dialled, like a phone number, is never read as one number at all — say each digit on its own, using oh for zero in British English, and double before a repeated digit (double three for 33).