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Subtract a pair of 2-digit numbers by finding the difference
I can subtract a pair of 2-digit numbers by finding the difference.
Lesson 6 of 10
New
New
- Year 3
Subtract a pair of 2-digit numbers by finding the difference
I can subtract a pair of 2-digit numbers by finding the difference.
Lesson details
Key learning points
- When the minuend and subtrahend are close in value, finding the difference can be an efficient strategy for subtraction
- Finding the difference means we count on from the subtrahend or count back from the minuend
- A number line or a bar model can represent finding the difference
Keywords
Minuend - The minuend is the number being subtracted from.
Subtrahend - A subtrahend is a number subtracted from another.
Difference - The difference is the result after subtracting one number from another.
Common misconception
Pupils will often try to use a written method/algorithm which they know gives an accurate answer but don't understand why it works.
Encourage the pupils to be brave and remind them that this is about mental subtraction so, with practice, will be quicker than any written methods.
This strategy is shown with number lines and jottings but the end goal is for the children be able to do it mentally so try to reduce such supports as quickly as possible.
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
6 Questions
Q1.What number is represented by these place value counters?
What number is represented by these place value counters?
10
433
Q2.What number is represented by the base ten blocks?
What number is represented by the base ten blocks?
442
10
424
Q3.Choose the correct symbol to go between the expressions. 7 + 5 ___ 3 + 4
Choose the correct symbol to go between the expressions. 7 + 5 ___ 3 + 4
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=
Q4.Choose the correct symbol to go between the expressions. 20 − 3 ___ 12 + 10
Choose the correct symbol to go between the expressions. 20 − 3 ___ 12 + 10
>
=
Q5.Choose the correct symbol to go between these expressions. 34 − 10 ___ 14 + 10
Choose the correct symbol to go between these expressions. 34 − 10 ___ 14 + 10
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Q6.Using your understanding of place value, order these numbers from smallest to greatest.
Using your understanding of place value, order these numbers from smallest to greatest.
Assessment exit quiz
6 Questions
Q1.Match the numbers with words for the equation 8 − 6 = 2
Match the numbers with words for the equation 8 − 6 = 2
Q2.Which of these bar models represents finding the difference?
Which of these bar models represents finding the difference?
Q3.Which of these contexts does not involve finding the difference?
Which of these contexts does not involve finding the difference?
How many more sweets have I eaten?
How many more sweets do I have compared to you?
Q4.Which of these subtraction expressions can be more efficiently solved by finding the difference?
Which of these subtraction expressions can be more efficiently solved by finding the difference?
81 − 43
45 − 16
Q5.67 − 58 =
67 − 58 =
Q6. = 96 − 89
= 96 − 89
