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

Starter quiz

What is the missing value? 8 tens + ______ tens = 13 tens.
- '5' ✓
What are the addends in this calculation: 90 + 30 + 10 = 130
- 90, 10 and 130
- 130, 90 and 10
- 90, 30 and 10 ✓
- 30, 10 and 130
If I know 6 + 7 = 13, what is 6 tens + 7 tens? ______
- '13 tens' ✓
Match the linked equations. Which number facts would you use to solve each equation with multiples of 10?
- 3 + 8 = 11
  
  ⇔
  
  30 + 80 = 110 ✓
- 4 + 9 = 13
  
  ⇔
  
  40 + 90 = 130 ✓
- 5 + 7 = 12
  
  ⇔
  
  50 + 70 = 120 ✓
- 6 + 7 = 13
  
  ⇔
  
  60 + 70 = 130 ✓
What is the sum of these addends 40 + 60 + 50 = ______
- '150' ✓
What is the missing addend 80 + ______ + 40 = 140?
- '20' ✓

Which number is the subtrahend in this calculation? 150 - 70 = 80
- '70' ✓
Which number is the minuend in this calculation? 130 − 50 = 8 tens
- '130' ✓
Match the known number fact to its related multiple of ten.
- 15 - 9 = 6
  
  ⇔
  
  150 - 90 = 60 ✓
- 14 - 6 = 8
  
  ⇔
  
  140 - 60 = 80 ✓
- 13 - 6 = 7
  
  ⇔
  
  130 - 60 = 70 ✓
- 12 - 5 = 7
  
  ⇔
  
  120 - 50 = 70 ✓
- 16 - 8 = 8
  
  ⇔
  
  160 - 80 = 80 ✓
Calculate 120 - ______ = 80
- 40 ✓
- 20
- 80
Which partitioned subtrahend will help you to bridge 100?
- 110 - 50
  
  ⇔
  
  50 = 10 + 40 ✓
- 120 - 50
  
  ⇔
  
  50 = 20 + 30 ✓
- 130 - 50
  
  ⇔
  
  50 = 30 + 20 ✓
- 140 - 50
  
  ⇔
  
  50 = 40 + 10 ✓
How would the subtrahend 70 be partitioned in this equation?
- 40 and 30
- 50 and 20
- 60 and 10 ✓

The language of unitising helps us to use number facts to 20 to subtract multiples of 10 crossing the hundreds.
If 14 subtract 6 is equal to 8 then 14 tens subtract 6 tens is equal to 8 tens or 80.
Partitioning the subtrahend helps us to cross the 100s boundary.

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 and related subtraction facts is secure or supported so that pupils can apply them.

Subtrahend - The number that is to be subtracted. The second number in a subtraction.
Minuend - The first number in a subtraction. The number from which another number is to be subtracted.