Division undoes multiplication

Hello, and welcome to Myriora Maths! Four fives make twenty. But can you go backwards? Twenty divided by five: what is it? Here's the secret: division undoes multiplication!

Think of a machine. Put in four, times by five, and out comes twenty. Now run it backwards. Put in twenty, divide by five, and you're back to four! Divide undoes times, like walking back the way you came.

Here are twenty counters, in four rows of five. Four rows of five is four times five: twenty. Now, how many fives are in twenty? Count the rows: one, two, three, four! So twenty divided by five is four. And how many fours are in twenty? Count the columns: five. Twenty divided by four is five.

So one picture gives four facts. Four times five is twenty. Five times four is twenty. Twenty divided by five is four. And twenty divided by four is five. They're a fact family: the same three numbers, every time.

So to divide, use your times tables backwards. What is twenty-four divided by three? Ask yourself: what times three makes twenty-four? Count up in threes: three, six, nine, twelve, fifteen, eighteen, twenty-one, twenty-four. That's eight threes. So twenty-four divided by three is eight, because eight times three is twenty-four.

Let's try one together. What is eighteen divided by two? Think: what times two makes eighteen? Say it out loud!

Nine times two is eighteen. So eighteen divided by two is nine! Well done if you said nine!

Here's a question that catches lots of people. Is twenty divided by four the same as four divided by twenty? With times, you can swap the numbers round. So some people swap them for divide too. But you can't! Twenty sweets shared by four children is five each. Four sweets shared by twenty children: they don't even get one each!

Your turn! What is thirty divided by six? Think: what times six makes thirty? Pick the right card. You've got fifteen seconds, or pause the video. Go!

Time's up! Count up in sixes: six, twelve, eighteen, twenty-four, thirty. That's five sixes. So thirty divided by six is five!

Quick review. Division undoes multiplication. To divide, ask: what times this number makes that one? Use your times tables backwards. And remember, you can't swap the numbers round in a divide. See you next time!