Use number bonds to 10 to add/subtract one-digit and two-digit numbers | Maths

Starter quiz

Choose the bar model that represents this problem. After Sam had watered the flowers, there was 73 ml of water in the jug. Alex adds 5 ml more. How much water is in the jug now?
Which known fact would you use to solve this problem? Alex’s packet of seeds weighed 67 g and Sam’s weighed 4 g less. What did Sam’s packet of seeds weigh?

7 − 4 = 3 ✓

6 − 4 = 2

7 − 6 = 1
Which equation could represent the problem shown? Alex spent 46 p and Sam spent 49 p. Use the equation to work out the difference between the amounts they spent.

46 + ___= 49 ✓

49 − ___ = 46 ✓

46 + 49 = ___
Use the bar chart to answer the question. How many people visited the park on Monday and Tuesday altogether? Use a known fact to help you solve the problem.

'59' ✓
Use the bar chart to answer the question. How many more visitors were there on Thursday than Friday? Use a known fact to help you solve the problem.

'4' ✓
Use the bar chart to answer the question. Saturday had two fewer visitors than Tuesday. How many visitors will be shown on the bar chart once the bar is drawn for Saturday?

'54' ✓

Exit quiz

Alex represents the equation 34 + 6 = ___ Which known fact could he use to solve this efficiently?

5 + 5 = 10

4 + 6 = 10 ✓

7 + 3 = 10

8 + 2 = 10
Use the picture to complete the stem sentence. We know that 5 plus 5 is equal to 10, so we also know that ______ plus 5 is equal to 30

'25' ✓
Which of the following numbers will complete the equation? 76 + 4 = ___

70

50

80 ✓
Which equation would be next in this pattern? 63 + 7 = 70, 73 + 7 = 80, 83 + 7 = 90 ...

93 + 7 = 100 ✓

53 + 7 = 60

83 + 8 = 100
Which equation would be next in this pattern? 41 + 9 = 50, 42 + 8 = 50, 43 + 7 = 50 ...

53 + 7 = 50

44 + 7 = 50

44 + 6 = 50 ✓
In my equation, I subtracted a number with a ones digit of 9 from a multiple of ten. How many ones are there in the difference? ______ one.

'1' ✓

Worksheet

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Lesson Details

Key learning points

When the ones digits in an equation sum to ten, the sum in the equation will always be a multiple of ten.
When subtracting a one-digit number from a multiple of ten, number bonds to ten can be used.
The number being subtracted and the ones digit in the answer will be a number bond to ten.

Common misconception

When subtracting, children may use their number bonds to ten to find the correct ones digit, but may forget to consider the previous multiple of ten, e.g. say 40-2=48

Encourage children to use their knowledge of decades to estimate (e.g. I know 40-2 will be in the thirties), then prove it using representations that highlight the tens structure, e.g. one hundred squares, ten frames and number lines.

Keywords

Sum - The result of adding two or more numbers
Difference - The result of subtracting one number from another. How much one number differs from another.