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Lesson 2 of 10
Lesson 2 of 10
New
New
Composition of 100 in 50s, 25s and 20s
I can compose 100 in 50s, 25s and 20s.
Lesson details
Key learning points
- 100 can be divided into equal parts
- There are two 50s in 100
- There are four 25s in 100
- There are five 20s in 100
Keywords
Compose - You can compose larger numbers from smaller numbers.
Decompose - You can decompose whole numbers into smaller numbers.
Common misconception
Pupils may believe only multiples of 10 can compose 100 and therefore do not see four groups of 25.
Focus on practical representations e.g. bead strings and base 10 blocks where 100 can be composed and decomposed.
Multiplication equations are used to represent compositions of 100. Take time to connect these to arrays, repeated addition and ways of saying multiplication including groups of.
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.What numeral represents one hundred?
What numeral represents one hundred?
1
10
Q2.Which expression is equivalent to 10?
Which expression is equivalent to 10?
1 × 100
10 × 10
Q3.Match the equivalent amounts.
Match the equivalent amounts.
80
30
100
70
50
Q4.100 = x 1
100 = x 1
Q5.Which equation is equal to 100?
Which equation is equal to 100?
10 + 10
10 x 1
Q6.If 100 decomposed into ten equal parts there will be in each part.
If 100 decomposed into ten equal parts there will be in each part.
100
1
Assessment exit quiz
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6 Questions
Q1.How many tens is 100 composed of?
How many tens is 100 composed of?
Q2.100 can be decomposed into how many tens?
100 can be decomposed into how many tens?
100
1
Q3.Complete the equation: 50 × = 100
Complete the equation: 50 × = 100
Q4.100 can be composed of 4 equal parts. How many ones are in each part?
100 can be composed of 4 equal parts. How many ones are in each part?
4
20
50
100
Q5.One hundred is composed of five equal parts. How many ones are in each part?
One hundred is composed of five equal parts. How many ones are in each part?
Q6.Complete the calculation: 100 = 25 x
Complete the calculation: 100 = 25 x