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Lesson · Grade 3 · Mathematics

Subtracting Three-Digit Numbers: Trade a Ten for Ten Ones

  • Grade 3
  • Mathematics
  • 1 min 5 s
  • British Columbia
  • BC3-MA-08

To work out 452 − 137, the video starts with the ones: there are only 2 ones, not enough to take away 7, so one ten rod breaks into 10 ones cubes, making 4 tens and 12 ones. It then subtracts each column (12 − 7 = 5, 4 − 3 = 1, 4 − 1 = 3) with matching base ten blocks, checks that 315 + 137 = 452, and ends on the recap: when there are not enough ones, trade 1 ten for 10 ones.

Concept: Subtracting three-digit numbers with regrouping

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In one sentence

The question this lesson answers

What is 452 minus 137?

452 is 4 hundreds, 5 tens and 2 ones.

Transcript

What the lesson says

What is 452 minus 137?

452 is 4 hundreds, 5 tens and 2 ones.

Start with the ones: take 7 away from 2.

There are only 2 ones, not enough to take away 7.

So trade 1 ten for 10 ones.

Now there are 4 tens and 12 ones.

12 minus 7 is 5.

Next, the tens: 4 minus 3 is 1.

Last, the hundreds: 4 minus 1 is 3.

So 452 minus 137 is 315.

Check by adding: 315 plus 137 is 452.

When there are not enough ones, trade 1 ten for 10 ones.

Curriculum

Where this fits

British Columbia, Grade 3

Mathematics, Number: addition and subtraction to 1000BC3-MA-08

Previous: Adding Three-Digit Numbers with RegroupingNext: Friendly Numbers: Estimate First, Then Adjust

The outcomes and strands follow the British Columbia curriculum.

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