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Lesson · Grade 7 · Mathematics

Multiply by 9: Times 10, Then Take One Group Away

  • Grade 7
  • Mathematics
  • 52 s
  • British Columbia
  • BC7-MA-03

The video shows 7 × 9 as 9 groups of 7 blocks, adds a tenth group so that 10 groups of 7 make 70, then takes that extra group of 7 away to leave 63. It warns students to take away 7, not 9, and ends on the recap: to multiply by 9, multiply by 10, then take one group away.

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In one sentence

The question this lesson answers

What is 7 times 9?

We can think of 7 times 9 as 9 groups of 7.

Transcript

What the lesson says

What is 7 times 9?

We can think of 7 times 9 as 9 groups of 7.

9 is just one less than 10.

So add one more group of 7. That makes 10 groups.

So we can multiply by 10, then take one group away.

Step 1: multiply 7 by 10.

10 groups of 7 make 70.

Step 2: take one group away.

One group is 7, so we take away 7, not 9.

70 take away 7 is 63.

So 7 times 9 is 63.

To multiply by 9, multiply by 10, then take one group away.

Curriculum

Where this fits

British Columbia, Grade 7

Mathematics, Number: multiplication and division facts to 100BC7-MA-03

Previous: Multiply by 4 and by 8 by doublingNext: Break a number apart to multiply

The outcomes and strands follow the British Columbia curriculum.

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