New
New
Year 3

Subtract 2 or 3-digit numbers using partitioning and bridging a multiple of 10

I can subtract 2 or 3-digit numbers using partitioning and bridging a multiple of 10

New
New
Year 3

Subtract 2 or 3-digit numbers using partitioning and bridging a multiple of 10

I can subtract 2 or 3-digit numbers using partitioning and bridging a multiple of 10

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Lesson details

Key learning points

  1. By looking at the minuend and subtrahend we know if we will have to bridge 10 or 100
  2. If the ones digit of the subtrahend is greater than the ones digit of the minuend then we will have to bridge through 10
  3. If the 10s digit of the subtrahend is greater than the 10s digit of the minuend then we will have to bridge through 100

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.

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.

  • Partition - Partition is the act of splitting an object or value down into smaller parts.

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 (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
How many pentagons are there in this group of polygons?
An image in a quiz
1
2
Correct answer: 3
4
5
Q2.
What is the product of 2 and 10?
Correct Answer: 20
Q3.
= 15 − 9
Correct Answer: 6, six
Q4.
= 25 − 19
Correct answer: 6
Correct answer: six
Q5.
Which of the following expressions give a difference of six?
26 − 19
Correct answer: 10 − 4
100 − 4
27 − 10
Correct answer: 13 − 7
Q6.
207 − 190 =
Correct Answer: 17, seventeen

6 Questions

Q1.
Which is the correct definition of difference?
The result after adding one number to another.
The result after multiplying two or more numbers.
The result after dividing one number by another.
Correct answer: The result after subtracting one number from another.
Q2.
What subtraction equation does this number line represent?
An image in a quiz
75 + 24 = 99
75 − 20 = 55
Correct answer: 75 − 24 = 51
75 − 51 = 24
Q3.
Find the difference between 270 and 160 using partitioning.
Correct Answer: 110, one hundred and ten
Q4.
Find the difference between 430 and 310 using partitioning.
Correct Answer: 120, one hundred twenty
Q5.
Find the difference between 540 and 360 using partitioning and bridging.
Correct Answer: 180, one hundred and eighty
Q6.
Find the difference between 670 and 490 using partitioning and bridging.
Correct Answer: 280, two hundred and eighty