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Lesson · Grade 7 · Mathematics

2.4 × 1.3

  • Grade 7
  • Mathematics
  • 1 min 37 s
  • British Columbia
  • BC7-MA-17

Concept: Multiplying decimals

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In one sentence

The question this lesson answers

How do we multiply 2.4 by 1.3? Let us find out.

First, set the decimal points aside for now. We will put the point back at the end.

Transcript

What the lesson says

How do we multiply 2.4 by 1.3? Let us find out.

First, set the decimal points aside for now. We will put the point back at the end.

Now multiply 24 by 13, just like whole numbers.

Start with the 3 in the ones place. Multiply each digit of 24 by 3, from right to left.

3 times 4 is 12. Write 2 and carry 1.

3 times 2 is 6, plus the 1 we carried makes 7.

So 24 times 3 is 72.

Next comes the 1. It is in the tens place, so it is worth 10. First, write a 0 in the ones place.

1 times 4 is 4, and 1 times 2 is 2.

So 24 times 10 is 240.

Now add the two rows, starting from the right.

7 plus 4 is 11. Write 1 and carry 1.

So 72 plus 240 is 312.

Now count the decimal places. 2.4 has 1 decimal place, and 1.3 has 1. That makes 2 altogether.

So the answer needs 2 decimal places. Start at the right of 312 and hop the point 2 places to the left.

So 2.4 times 1.3 equals 3.12.

Curriculum

Where this fits

British Columbia, Grade 7

Mathematics, Number: operations with decimalsBC7-MA-17

Previous: 15.2 − 7.85Next: 7.56 ÷ 0.12

The outcomes and strands follow the British Columbia curriculum.

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