Today’s problem — free all day, every step. Every day has one.
Mrs Lim's withdrawal — half to her son
Mrs Lim withdrew some money from the bank. She gave half of it to her son for his tuition fees. She then spent $24 on groceries and was left with $16. How much money did Mrs Lim withdraw at first?
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65 worked examples are free without a code, two from every pattern. No account, either way.
The pattern behind it: Working backwards
You know how it ended. Undo each step, last one first.
In this one. Work backwards: add what was spent to what remained to rebuild the kept half, then double that half to recover the whole.
How to spot it
The question gives the final amount after a sequence of changes and asks what the amount was 'at first' or 'to begin with'.
Common mistake
Children undo the steps in the same order they happened rather than in reverse, or forget that a percentage profit is added to the cost price, so the final price is 120% of it, not 100%.
Try one like it
Standard Ivan and Helen — half his money Ivan gave half of his money to Helen. He then spent $18 and was left with $12. How much money did Ivan have at first?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.
A PDF, and a note when new solutions go up.