Quantities, Fractions & Measurements

Half the cake is gone — but half the biscuits are gone. Read those two lines again, because something odd is happening. The word half hasn't changed, and yet the verb flips from is to are. That's what makes fractions and amounts genuinely confusing: you can't decide the verb just by looking at the number word itself. Students often assume that a word like half, most or some is either singular or plural once and for all — but it isn't. When a fraction or an amount is the subject of a sentence, the verb depends on what the amount is made of, not on the fraction word out front. Once you know where to look, these sentences stop being a guessing game.

The rule: look at what follows "of"

For fractions, percentages and quantity words like some, all, most, half, a lot of, the rest of, the verb agrees with the noun that comes after "of":

Half of the cake is gone. (cake → can't be counted → singular) Half of the biscuits are gone. (biscuits → countable, plural → plural)

So the same word, half, can take is or are depending entirely on what it's measuring. This is why you can't answer these on autopilot. The trick is to slide your eye past the fraction and land on the real noun — cake or biscuits — and let that noun decide. A useful phrase to remember: the fraction is just the messenger; the noun after "of" gives the order.

More examples

Most of the water has dried up. (water → one mass → singular) Most of the students have left. (students → countable → plural) 50% of the class is absent. (class → one group → singular) Two-thirds of the players were injured. (players → plural)

Line these up and the pattern is clear: whenever the of noun is something you'd count one by one (students, players, biscuits), you get a plural verb; whenever it's a single lump you'd measure rather than count (water, cake, sugar, class), you get a singular verb. If you've met countable and uncountable nouns before, this is the very same split doing a new job.

Measurements, money and time → singular

Now for a group that behaves in a surprising way. When an amount is treated as one whole quantity — a single price, a single length, a single stretch of time — it takes a singular verb, even though the number in front looks plural:

Ten pounds is a lot for a sandwich. · Five miles is a long walk. · Two hours is enough revision for one night.

At first glance ten pounds looks plural, so surely it's are? But you're not thinking of ten separate coins lined up — you're thinking of one price, one total, one amount. Treat it as a single block of money, distance or time, and the singular verb is falls into place. The same goes for weight (three kilos is heavy) and for maths results (two plus two is four).

Watch out — it's the "of" noun that decides

The commonest slip is to be hypnotised by the number and ignore the noun that actually matters:

✓ Three-quarters of the pizza was eaten. (pizza → one thing → singular) ✓ Three-quarters of the slices were eaten. (slices → countable → plural)

Notice that three-quarters didn't decide anything on its own — pizza and slices did. So before you commit to a verb, always finish reading the subject. Find the noun after of, ask "is this one lump or several countable things?", and only then choose. It's a two-second check that saves a very common mistake.

An edge case: "a number of" vs "the number of"

Here's a neat pair that looks almost identical but splits cleanly. A number of means "several", so it's plural: A number of pupils are waiting. But the number of points at the single figure itself, so it's singular: The number of pupils is rising. The tiny word a or the flips the whole verb. It feels fussy, but it's a favourite in tests, and once you've seen it you won't forget it.

A second angle: think of the fraction as a window

If the "look after of" rule ever slips your mind, try picturing the fraction word as a little window you look through rather than at. When you say most of the cake, you're not really talking about "most" as a thing — you're looking through the word most at the cake behind it, and it's the cake you're describing. So you match the verb to whatever you can see through the window. Through half you might see a plural crowd of biscuits, or a single lump of cake; through most you might see water or students. Whatever's framed in that window is the thing the verb agrees with. It's the same rule as before, just a picture to help it stick — and pictures, as any teacher will tell you, tend to stay put in your memory far longer than a bare instruction does.

Why it matters

Amounts, fractions and percentages turn up everywhere the moment your writing gets more grown-up — in science write-ups (most of the sample was dissolved), in maths and data (40% of the results were unusual), in geography, in history essays about populations and dates. These are exactly the subjects where a marker is reading closely and expecting precision, so a mismatched verb stands out more than usual. Getting agreement right here makes your factual writing read as careful and controlled, which is precisely the impression you want to give. And because the rule rests on one clear question — what is this an amount of? — it's completely learnable. You're not memorising a list; you're training yourself to look one word further along before you pick the verb.

Quick check

is or are?

1. Half of the apples ___ rotten.

2. Twenty pounds ___ too much.

3. Most of the cheese ___ mouldy.

4. Three-quarters of the audience ___ children.

5. Six weeks ___ a long time to wait.

6. A number of students ___ still missing.

Where next

• Subject–Verb Agreement — the core rule.
• Some/Any/Much/Many/Fewer/Less — countable vs uncountable.
• Notional Concord — meaning-based agreement.