Percentages of amounts

Hello, and welcome to Myriora Maths! What is thirty-five per cent of eighty pounds? It sounds hard. But you only need three easy building blocks: ten per cent, five per cent and one per cent.

To find ten per cent, divide by ten. Ten per cent of eighty pounds is eight pounds. That works because ten per cent is one tenth.

Five per cent is half of ten per cent. Half of eight pounds is four pounds. And for one per cent, divide by a hundred. One per cent of eighty pounds is eighty pence.

Now let's build thirty-five per cent. Thirty per cent is three lots of ten per cent: three times eight pounds is twenty-four pounds. Then add five per cent, which is four pounds. Twenty-four add four is twenty-eight pounds!

You can build any percentage like this. Some have shortcuts. Fifty per cent is a half, and twenty-five per cent is a quarter. And ninety per cent is the whole amount, take away ten per cent.

Let's try one together. What is twenty per cent of sixty pounds? Say it out loud!

Ten per cent of sixty pounds is six pounds. Twenty per cent is two lots of that: twelve pounds!

Here's a question that catches lots of people. What is five per cent of forty pounds? Some people divide by five, and get eight pounds. But dividing by five gives twenty per cent! Ten per cent is four pounds, so five per cent is half of that: two pounds.

Your turn! What is fifteen per cent of sixty pounds? Pick the right card. You've got twenty seconds, or pause the video. Go!

Time's up! Ten per cent is six pounds, and five per cent is three pounds. Six add three is nine pounds!

Quick review. For ten per cent, divide by ten. Five per cent is half of ten per cent. For one per cent, divide by a hundred. Then build any percentage from these blocks. See you next time!