Number Β· a fair way to share

A fraction is just a fair way to share a pizza.

The bottom number says how many equal slices. The top says how many you take. That's the whole secret β€” let's slice into it.

Grab a slice
The whole idea

One pizza, shared fairly.

A fraction is a part of a whole. Cut a pizza into equal slices, take a few, and the fraction tells the story: how many you took, out of how many equal slices there were.

That's it. Every scary-looking fraction you'll ever meet is really just this β€” a whole thing, chopped into fair pieces, with some of them claimed. Hold that pizza in your head and the rest of this page will feel like sharing a snack with friends.

The two numbers

Top and bottom each have a job.

Write a fraction and you'll see two numbers with a little line between them. They aren't random β€” each one answers a different question, and once you know which is which, fractions stop being mysterious.

Bottom = denominator

How many equal slices the whole was cut into. A bigger denominator means more slices β€” so each slice is smaller. (Tip: denominator = down below.)

Top = numerator

How many of those slices you actually take. It counts the pieces you're holding out of the total below it.

So take 34 of a pizza. The 4 on the bottom says the pizza was cut into 4 equal slices. The 3 on top says you grabbed 3 of them. Three slices out of four β€” we read it aloud as three quarters. You can almost taste it: most of the pizza is yours, with just one slice left in the box.

Try a different snack. A chocolate bar snapped into 5 equal squares, and you nibble 2 of them: that's 25, read as two fifths. The 5 set how big each square is; the 2 counted the ones you ate. Notice the recipe never changes β€” the bottom builds the pieces, the top counts the ones you keep. Once you spot that pattern, you can read any fraction on sight.

Read it like a sentence. Bottom first to set the size of the slices, then top to count them. 34 = "cut into 4, take 3." Try saying any fraction that way and it instantly makes sense.
Try it Β· 01

Slice your own pizza.

This is the whole idea you can touch. Slide the bottom control to cut more or fewer equal slices, then slide the top control to take some. Watch the fraction β€” and the words for it β€” change as you go. Switch between a round pizza and a straight chocolate bar; the maths is identical.

slide to cut & take
4
3
34 3 of 4 slices = three quarters
The bottom number cut the pizza into 4 equal slices; the top number took 3 of them.

Notice you can never take more slices than exist β€” the top control stops at the bottom number. Take all the slices and you've got one whole pizza again.

The fine print

Equal parts, or it isn't a fraction.

Here's the one rule that holds everything together: the slices must be equal. If your friend hacks the pizza into 4 wildly different chunks β€” one huge, three tiny β€” and hands you "1 out of 4," you have not been given one quarter. You've been robbed.

The fraction 14 only means something when each of the 4 pieces is exactly the same size. That's why every slice in the demo above is cut to be identical: a fraction is a promise of fairness. When you see "a quarter of the class" or "half the cake," it always assumes the whole was split into truly equal parts. No equal parts, no honest fraction.

Picture it: a bar broken into one giant chunk and three slivers. Someone hands you a sliver and calls it "one of four pieces." The count is right β€” it really is 1 of 4 β€” but it isn't 14, because a true quarter would be a quarter of the whole bar, and that sliver is nowhere near. The lesson sticks: a fraction counts equal pieces, so always check the pieces are equal before you trust the number.

Quick gut-check: if you could rearrange the pieces and someone would feel cheated, the slices weren't equal β€” and the fraction is a fib.
Try it Β· 02

Same amount, different cut.

Here's something that feels like magic but is just common sense. Cut a bar in half and shade one piece: that's 12. Now slice each piece again so there are twice as many β€” you have to shade two of them to cover the same space, giving 24. Different numbers, exactly the same amount of bar. These are equivalent fractions. Watch the shaded edges line up perfectly no matter how fine you cut.

same shaded width, finer cuts
2
1
2

Multiply the top and bottom by the same number and the value doesn't change β€” you've just drawn extra cut-lines through pieces that were already there. Going the other way (dividing top and bottom by the same number) is called simplifying.

Here's the trick in plain numbers. Start with 12. Multiply top and bottom by 2 and you get 24; by 4 and you get 48 β€” a whole family of fractions that all mean the very same half. Run the trick backwards and you're simplifying: 68 has a 2 hiding in both the top and the bottom, so divide each by 2 to get 34 β€” the same amount, written as simply as it'll go. That's why we'd usually say "three quarters" rather than "six eighths," even though they fill the same plate.

Try it Β· 03

Which slice is bigger?

To compare two fractions fairly, they have to be slices of the same whole β€” two bars the same length. Set up two fractions below and the demo shades each one and tells you which is larger. Try 12 against 23, then chase down a tie.

two bars, same whole
1
2
2
3

If the two bars were different lengths, the comparison would be meaningless β€” like asking whether half a cupcake beats a quarter of a wedding cake. Same whole first, then compare.

You won't always have bars to hand, so keep two shortcuts in your pocket. When the bottoms match, the slices are already the same size β€” so just compare the tops: 38 beats 28. When the tops match, you're taking the same number of slices, so the one with the smaller bottom (bigger slices) wins: 34 beats 35. And when nothing matches, re-cut both into the same number of slices first β€” a shared bottom β€” then compare the tops. That's the equivalent-fractions trick doing real work.

Going deeper

Two more faces of a fraction.

Once the pizza makes sense, a fraction quietly reveals two extra disguises. You don't need to master these yet β€” just meet them, so they feel familiar later.

A fraction is a division waiting to happen.

The line in a fraction is really a "divide" sign in disguise. 34 literally means 3 Γ· 4 β€” share 3 pizzas equally among 4 people. Tap it into a calculator and you get 0.75. That's why fractions and decimals are just two ways of writing the same amount: three quarters and 0.75 are the very same slice.

Picture that share-out for real. Three whole pizzas, four hungry friends. Give everyone half a pizza first (that uses up two pizzas), then cut the last pizza into four and hand one quarter to each. Every friend ends up with one half plus one quarter β€” which is three quarters of a pizza each. So 34 isn't just a symbol; it's the honest answer to "what does each person get when 3 is shared fairly among 4?" Division and fractions are the same question wearing different clothes.

A fraction is a place on the number line.

Fractions don't only live on plates β€” they also sit at exact spots between the whole numbers. Picture the stretch from 0 to 1 as one pizza laid out flat. Cut it into 4 equal steps and 34 is the third step along: three-quarters of the way from 0 to 1.

0 ΒΌ Β½ ΒΎ 1

Same idea as the pizza, just stretched into a straight line: the bottom number sets how many equal steps fit between 0 and 1, and the top number counts how far along you land.

Don't be fooled

The trap: "bigger bottom number = bigger fraction."

This one catches almost everyone, because for whole numbers bigger really does mean bigger. Fractions flip your instinct on its head β€” so it's worth meeting the trap head-on.

The famous mix-up
A fifth must be bigger than a third β€” 5 is bigger than 3!
No β€” bigger bottom, smaller piece

Think about the pizza. Cutting it into 5 slices makes each slice smaller than cutting it into 3, because you're sharing the same pizza among more pieces. So 15 is actually smaller than 13. More slices means each one is daintier β€” the bottom number measures how small, not how big.

A sneaky cousin
To add fractions, just add the tops and add the bottoms.
Only equal slices can be counted together

It's tempting to say 12 + 12 = 24 β€” but that's clearly wrong, because two halves make a whole, not a quarter! You can only count slices together when they're the same size. Half plus half is one whole, full stop. Match the slice sizes first; that's what the bottom numbers are for.

Your turn

Mini slice-challenge.

Four quick questions. Tap an answer and you'll see straight away whether it holds up β€” and why. Your score climbs as you go: 0 / 4.

Carry this with you

Fractions, in three moves.

1

Cut equally

The bottom number cuts the whole into that many equal slices.

2

Take some

The top number counts how many of those slices you take.

3

Compare fairly

Same whole, same-sized slices β€” then bigger really does mean more.