What does per cent mean?

Hello, and welcome to Myriora Maths! You've probably seen signs in shops that say: fifty per cent off! But what does per cent actually mean? Let's find out.

Per cent means out of a hundred. Here's a square cut into a hundred small squares. Thirty of them are coloured. That's thirty out of a hundred, so it's thirty per cent. We write it with this sign.

All one hundred squares is one hundred per cent: the whole thing. Fifty per cent is fifty out of a hundred: exactly half. And twenty-five per cent is a quarter.

The word cent means a hundred. A century is a hundred years, and a centimetre is one hundredth of a metre.

What if something is out of ten? Here, seven out of ten strips are coloured. Cut each strip into ten small squares, and it's seventy out of a hundred. So seven out of ten is seventy per cent!

Let's try one together. Here are a hundred squares, and forty-five of them are coloured. What per cent is that? Say it out loud!

Forty-five out of a hundred is forty-five per cent!

Here's a question that catches lots of people. Three out of ten children wear glasses. What percentage is that? Some people say three per cent. But it's out of ten, not out of a hundred. Three out of ten is thirty out of a hundred: thirty per cent!

Your turn! A hundred square has sixty squares coloured. What per cent is not coloured? Pick the right card. You've got twenty seconds, or pause the video. Go!

Time's up! Sixty are coloured, so forty out of a hundred are not. That's forty per cent!

Quick review. Per cent means out of a hundred. One hundred per cent is the whole, and fifty per cent is a half. Seven out of ten is seventy out of a hundred, so it's seventy per cent. See you next time!