Bridge 100 by adding in multiples of 10 | Maths | Quizalize & Oak National Academy

Starter quiz

What is the missing part on the bar model?

120

100

20 ✓
What is the missing whole on the bar model?

132

130

150 ✓

120
Use this bar model. Which addition calculations are correct?

9 tens = 19 tens + 10 tens

9 tens + 10 tens = 19 tens ✓

19 tens = 10 tens + 9 tens ✓

9 tens + 19 tens = 10 tens
170 = 40 + 100 + ______. What is the missing part?

'30' ✓
Sofia buys some ribbon that is 170 cm long. She gives 70 cm to her friend. How much does she have left ? ______ cm.

'100 ' ✓
Which calculations could represent this bar model?

140 = 40 + 100 ✓

100 - 140 = 40

100 + 40 = 140 ✓

100 = 140 - 40 ✓

100 - 40 = 140

What are the addends in this calculation 90 + 30 = 120 ?

30 and 120

90 and 30 ✓

90 and 120
If I know 6 + 5 = 11 what is 6 tens + 5 tens? ______

'11 tens' ✓
Match the tens to the multiples of ten.

3 tens + 9 tens

⇔

30 + 90 ✓

4 tens + 8 tens

⇔

40 + 80 ✓

5 tens + 7 tens

⇔

50 + 70 ✓

6 tens + 6 tens

⇔

60 + 60 ✓

7 tens + 4 tens

⇔

70 + 40 ✓
When adding 80 to 60, how can the addend 60 be partitioned to bridge 100?

10 + 50

20 + 40 ✓

30 + 30
Which addition is equivalent to 80 + 20 + 50?

80 + 50

80 + 70 ✓

20 + 50

80 + 20
A number has been partitioned into something and 40 to bridge 100. What is the missing addend? 70 + ______ + 50 = 150

'30' ✓

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The language of unitising helps us to use number facts to 20 to add multiples of 10 crossing the hundreds.
Crossing the tens boundary helps us to cross the 100s boundary if we think in tens.
Partitioning an addend helps us to cross the 100 boundary when adding.

Lack of fluency with number facts to 20 can hinder progress in applying them to multiples of ten.

Ensure that fluency with number facts to 20 is secure or supported so that pupils can apply them.

Addend - An addend means any of the numbers that are added together.
Bridging 100 - Bridging 100 means partitioning one addend to make a number bond to 100 then adding the remaining part.