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Lesson 4 of 10

Use known facts to find pairs of numbers that total 100

I can use known facts to find pairs of numbers that total 100

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Lesson 4 of 10
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Use known facts to find pairs of numbers that total 100

I can use known facts to find pairs of numbers that total 100

Lesson details

Key learning points

  1. Number facts to 10 can be applied to multiples of 10
  2. If 3 plus 2 is equal to 5 then 3 tens plus 2 tens is equal to 5 tens.
  3. When you add a single digit to a multiple of ten, only the ones digit changes.

Keywords

  • Total - A total is the result of adding.

  • 2-digit number - A 2-digit number refers to a value between 10 and 99. The number is made up of two digits which represent tens and ones.

Common misconception

Pupils lack fluency in pairs for 10 and so struggle to connect this to 2-digit numbers.

Promote fluency through games and chants and consider providing a scaffold of pairs for 10 for pupils to use which automaticity develops.

This lesson provides an opportunity to review, rehearse and apply pairs that total 10 in a different context. It is important that pupils see that they are using previously learned facts in a new way. Make that step in thinking clear in the lesson.
Teacher tip

Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Prior knowledge starter quiz

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6 Questions

Q1.
50 is composed of how many tens?

Correct Answer: 5 , 5 tens

Q2.
100 is composed of 7 tens and tens.

Correct Answer: 3, three

Q3.
What is the total of 60 and 4 tens?

40
140
Correct answer: 100
60

Q4.
If I know that 2 + 8 = 10 what else do I know?

Correct answer: 8 + 2 = 10
2 − 8 = 10
Correct answer: 10 − 2 = 8
8 + 10 = 2

Q5.
Izzy was running 100 m. She fell over at 60 m. How many more metres did she have to run?

Correct Answer: 40 , forty , 40 m, 40 metres

Q6.
30 + 2 tens + 50 = __________

Correct answer: 10 tens
8 tens
2 tens
5 tens

Assessment exit quiz

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6 Questions

Q1.
25 + 75 = ___

25
75
10
Correct answer: 100

Q2.
Which of these 2-digit numbers is a multiple of ten?

25
75
Correct answer: 50
100

Q3.
What is 100 subtract 6? Use the number square.

An image in a quiz
40
4 tens
14 tens
Correct answer: 94
96

Q4.
100 = 93 + ?

Correct Answer: 7, seven, 7 ones

Q5.
Two 2-digit numbers total 100. If the first number has 10 ones, the second number is ...

100
10
Correct answer: 90

Q6.
Do these addends total 100? 73 + 37

Yes, they total 100
No, because the one digits do not total 10
Correct answer: No, because the tens digits do not total 90

Lesson appears in

UnitMaths / Securing place value to 100 and applying to addition and subtraction

Maths

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