• Mathematics (secondary) - Secondary/KS4/GCSE (age 14-15 yrs)

    Q: What is 2/3 + 1/4?

    When adding or subtracting fractions, we must always start by putting the fractions over the same denominator, that is the number on the bottom half of the fraction. To do this, we need to find a number which we can divide by both the current denominators 3 and 4, i.e. we need to find the lowest common denominator of 3 and 4. In this case, the lowest common denominator is 12. So we need to change both fractions so that their denominator is 12. We will start by changing 2/3 to ?/12. To do this , we need to multiply the first denominator (3) by 4 to get 12, and so we also need to multiply the numerator by 4. So, we get 2x4=8 and the fraction becomes 8/12. We must always multiply the numerator by the same number as we multiply the denominator by. For the second fraction, 1/4, we need to multiply the first denominator (4) by 3 to get the second denominator (12), so we also need to multiply the numerator by 3, giving 1x3=3 and the fraction becomes 3/12. Now we have 8/12 + 3/12 = ? To add fractions which are already in the same denominator, as these fractions are, all we need to do is add the numerators together (8+3=11) and put it over the denominator which both fractions are already in (12) and so our final answer is 11/12.

    Maria

    Q&As by Maria (8)

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