3. Now answer the following questions using the quick method only. (Do the division in your copy.)


Find: a) 1 f)


– 4 of 12 =


–– 10 of 50 =


1


k) 1 p) 1 u) 1


–– 10 of 10 =


–– 10 of 60 =


– 4 of 24 =


Puzzler Discuss with friends and at home if you like.


Evelyn, Jim, Sheila and Seán were each having a different type of cream cake from the bakery. Afterwards, there was 1 doughnut left, 1


– 8 of a jam meringue left.


5


Jim ate the most, Seán ate the least and Evelyn ate more than Sheila. What type of cake did each person eat?


Working out the Whole Number when You Know a Fraction of it


If you knew what a fraction of a number was, would you be able to work out the whole number?


For example, if one half (1


– 2) of a chocolate


bar has 15 pieces, how many pieces has the whole bar?


If one quarter (1


– 4) of a chocolate bar has


2 pieces, how many pieces has the whole bar?


– 4 of a coffee slice left, 1


–– 10 of a cream


– 2 of a chocolate éclair left and


b) 1 g) 1 l)


– 8 of 56 =


1


q) 1 v) 1


– 2 of 98 =


– 4 of 76 =


– 8 of 24 =


– 8 of 40 =


c) 1 h) 1 m) 1 r)


–– 10 of 70 =


1 w) 1


– 8 of 96 =


– 2 of 16 =


–– 10 of 40 =


– 4 of 16 =


d) 1 1


i)


n) 1 s) 1 x) 1


–– 10 of 20 = e) 1


– 4 of 48 = j) 1


– 8 of 48 = o) 1


–– 10 of 100 =


– 2 of 2 =


– 4 of 96 =


– 2 of 58 =


– 8 of 72 = t) 1


–– 10 of 90 =


Here’s how to work it out:


One half of the whole number = 15, so two halves = 15 + 15. Answer = 30.


The whole bar has 30 pieces of chocolate.


1. Find the whole number. a) 1 c) 1 e) 1


112 Fractions 2


– 2 = 4, so the whole number =


– 4 = 5, so the whole number =


– 2 = 11, so the whole number =


Here’s how to work it out:


One quarter of the whole number = 2, so four quarters = 2 + 2 + 2 + 2. Answer = 8.


The whole bar has 8 pieces of chocolate.


b) 1 d) 1 f) 1


– 4 = 3, so the whole number =


– 2 = 12, so the whole number =


– 4 = 9, so the whole number =


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