Look at this shelf tag: a game costs €200 with 10% off. Roughly how much comes off the price? Have a think before anyone answers.

Now look at the second tag. It says 50% off, which means half price. If a €200 game is half price, what do you pay?

Each bar shows a percentage of a number, split into equal parts with one part shaded. Watch how the percentage matches a simple fraction, and see what the shaded part is worth each time.

Today we build percents on the bar together. We will work three, in order.

First, 20% of 50 as two tenth-parts. Next, 75% of 40 as a half-part plus a quarter-part. Last, 30% of 40 as three tenth-parts.

Before we shade each one, predict how big just one part will be.

Sometimes we know the part but not the whole. Watch how we work this one the other way around.

A jumper had 25% off, and the saving was €5. What was the original price?

25% means one quarter. So one quarter of the price is €5. A whole price is made of four quarters, so we need four of those €5 parts. That gives 4 × 5 = 20. The original price was €20.

Check it forwards: 25% of 20 is 20 ÷ 4 = 5. That matches, so €20 is right.