Explain what happens when you add and subtract ten to a multiple of ten | Maths

Starter quiz

What number comes next in the counting sequence? 30, 40, 50, ______

30

40

50

60 ✓
What number is missing in the counting sequence? 50, 60, ______, 80, 90

50

60

70 ✓

80

90
What number comes next in the backwards counting sequence? 30, 20, ______

10 ✓

20

30

40
What multiple of 10 is the arrow pointing to on this number line?

10

20

30 ✓

40

50
Which arrow shows the position of 90 on this number line?

a

b

c ✓
What is a good estimate for this multiple of 10 shown on the number line?

0

10 ✓

30

30

Exit quiz

What is the missing number?

30

40 ✓

50
Ten more than 50 is ______

40

50

60 ✓
Ten more than 40 is 50, so ten less than 50 is ______

30

40 ✓

50
Match the equation to the correct multiple of 10

40 + 10 =

⇔

50 ✓

80 - 10 =

⇔

70 ✓

70 + 10 =

⇔

80 ✓

20 - 10 =

⇔

10 ✓
Ten less than 70 is ______

60 ✓

80

70
Match the pairs of equations to complete the sentence. I know that ______ so ______

3 + 1 = 4

⇔

30 + 10 = 40 ✓

1 + 5 = 6

⇔

10 + 50 = 60 ✓

4 + 1 = 5

⇔

40 + 10 = 50 ✓

6 + 1 = 7

⇔

60 + 10 = 70 ✓

Worksheet

Loading worksheet ...

Presentation

Loading presentation ...

Video

Lesson Details

Key learning points

Ten can be added to or subtracted from a multiple of ten.
When you add ten to a multiple of ten the tens number increases by one
When you subtract ten from a multiple of ten the tens number decreases by one
If 3 + 1 is equal to 4 then 3 tens + 1 ten is equal to 4 tens which is equal to 40

Common misconception

Children may not see the link between adding ones and adding tens. They may add or subtract one instead of ten or muddle addition and subtraction, so may subtract ten instead of add ten to a number.

Reinforce understanding of unitising by describing each group of objects in ones or tens, e.g. five cubes plus 1 cube, 5 tens plus 1 ten and talk through what is happening. Show this with equipment in tens and ones such as straws or cubes.

Keywords

Increase - Make something bigger (in size or quantity).
Decrease - Make something smaller (in size or quantity).
Multiple - A multiple is the result of multiplying a number by another whole number.