Multiply and divide by 1 and multiply by 0

When you multiply by 1, the answer stays the same.

For example:

1 × 21 = 21 or 21 × 1 = 21

You can think of it as 21 lots of 1 or 1 lot of 21. They both equal 21.

1 × a number = that number or a number × 1 = that number.

This works with any number, including big, small or negative numbers!
For example:

• 1 × 20,000 = 20,000
• 1 × 2 = 2
• 1 × -2 = -2

A common mistake is to think that 1 × 1 = 2.

1 plus 1 is 2, but 1 times 1 is 1.

1 × 1 = 1

When you divide by 1 the answer also stays the same!

For example:

21 ÷ 1 = 21

Think of it as if you had to divide 21 into groups of 1. You would get 21 groups.

Or imagine sharing 21 carrots with 1 bear. The bear would get all 21 carrots.

That works with any number, including big, small or negative numbers!

For example:

• 20,000 ÷ 1 = 20,000
• 21 ÷ 1 = 21
• -2 ÷ 1 = -2

What do you think 1 ÷ 1 will be?

When you divide a number by 1, the answer is the number you started with.

1 ÷ 1 = 1

Multiplying by 0 always gives the answer 0. Whether you do 0 × or × 0, it will equal 0. For example:

21 × 0 = 0

Think of it as 21 lots of 0 or 21 lots of nothing.You could see it as adding 0 twenty-one times.This is why it will always equal 0.

0 × a number = 0 or a number × 0 = 0

This makes the 0 times table simple!

Have a go at this quiz to show your understanding of multiplying and dividing by 0 and 1.