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Mrs Tan's $72 — groceries then a gift
Mrs Tan had $72. She spent of it on groceries and of the remainder on a birthday gift. How much did she spend on the gift?
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The pattern behind it: Branching
The second fraction is of one piece, not of the whole.
In this one. Cut the original amount into 6 equal units: the groceries use 1 unit, leaving exactly 5 units, so 3/5 of the remainder is simply 3 of those same units.
How to spot it
A second fraction arrives after the first and is attached to a piece rather than to the whole — 'of the remainder', 'of what was left', or 'of the ones that were red'.
Common mistake
Children take the second fraction of the original total instead of the piece it was named against, which makes the amount come out too big.
Try one like it
Standard Ali's stickers — shared with Ben and Carol Ali gave 1/6 of his stickers to Ben and 2/5 of the remainder to Carol. If Ali had 90 stickers at first, how many did Carol receive…The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
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