lesson
Find one part, then several
1 · Learn
To find 3/8 of 40, first divide 40 by 8. One eighth is 5. Then take three parts: 3 × 5 = 15.
Sometimes a fraction of an amount is known and you need the whole. If 1/4 of a set is 6, all four quarters make 24. Decide which amount is the whole before calculating.
2 · Worked example
If 2/5 of a collection is 12, one fifth is 6, so five fifths are 30.
3 · Your turn
Find 5/6 of 42. If 1/3 of a length is 8 cm, find the whole length.
Check your answer
35; 24 cm.
4 · Apply your learning
Represent each problem with an equal-part bar and label the known and unknown amounts.
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