Video: KS2-M17 • Paper 1 • Question 32

(2/6) − (1/8) = _.

02:45

Video Transcript

Two-sixths subtract one-eighth equals what?

The denominators in this question are not the same. To add or subtract fractions, we need the denominator to be the same. To do this, we need to find the lowest common multiple of six and eight.

Six, 12, 18, 24, 30, 36, 42: these are multiples of six. Eight, 16, 24, 32, 40, 48, 56, 64, and 72 are multiples of eight. 24 is the lowest common multiple of six and eight. To convert two-sixths into twenty-fourths, we need to multiply the denominator by four because six multiplied by four equals 24. We need to do the same to the numerator, two multiplied by four. So two-sixths is equal to eight over 24.

To change the denominator from eighths to twenty-fourths, we need to multiply by three. And we do the same to the numerator as we do to the denominator. So one multiplied by three is three.

Now we can calculate eight over 24 take away three over 24. The denominator doesn’t change. So we just need to calculate eight take away three, which is five. So eight twenty-fourths take away three twenty-fourths equals five twenty-fourths or five over 24. So two-sixths take away one-eighth equals five over 24.

Two-sixths and one-eighth don’t have the same denominator. So we converted these fractions by finding the lowest common multiple of six and eight. Then we were able to calculate eight over 24 subtract three over 24 to give us our answer.

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