Use known facts and mental strategies to calculate with decimal numbers within and across a whole | Maths

Starter quiz

Tick the number facts that make 10.
- 4 + 7
- 2 + 8 ✓
- 9 + 1 ✓
- 7 + 3 ✓
- 6 + 4 ✓
Ten tenths are equal to ______
- '1' ✓
I know 7 − 5 = 2 so 700 − 500 = ______
- '200' ✓
Tick all of the equations that can represent this part-part-whole model.
- 6 + 4 = 10 ✓
- 10 = 6 − 4
- 6 = 10 + 4
- 6 = 10 − 4 ✓
- 10 − 6 = 4 ✓
I know 12 − 5 = 7 so 120 − 50 = ______
- 7
- 70 ✓
- 17
- 170
What are the missing numbers that the nine would need to be partitioned into to bridge 10 for this example.
- 3 and 6
- 2 and 7
- 4 and 5 ✓
- 1 and 8

I know 3 + 6 = 9 so 0.3 + 0.6 = ______
- '0.9' ✓
I know 8 − 5 = 3 so 0.8 − 0.5 = ______
- '0.3' ✓
Which of these pairs of numbers sum to make 1?
- 0.4 and 0.6 ✓
- 0.2 and 0.7
- 0.9 and 0.2
- 0.3 and 0.7 ✓
- 0.5 and 0.5 ✓
Use a known number fact to help you solve: 1 − 0.3 = ______
- '0.7' ✓
Fill in the missing number for the equation represented by the number line.
- '0.9' ✓
Fill in the missing number: ___ − 0.7 = 0.8
- '1.5' ✓

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If you know that 5 + 2 is equal to 7 then 5 tenths + 2 tenths is equal to 7 tenths so 0.5 + 0.2 = 0.7
Use known facts and unitising to add tenths.
Bridging 10 strategies with whole numbers can be applied when the tenths bridge one whole.

Pupils record missing part equations incorrectly.

Encourage children to match the equation to a representation identifying which number represents the wholes and which represent parts.

Number facts - Simple calculations using two numbers are known as number facts. For example 2 + 4 = 6
Bridging - Bridging is a mental strategy which uses addition or subtraction to cross a number boundary.