?
A very long time ago, at the beginning of the week, I was given some money for my birthday.
On Monday, I spent a quarter of the money on clothes.
On Tuesday, I spent one third of the remaining money on music.
On Wednesday, I spent half of the remaining money on food.
Finally, on Thursday, I spent the last £12.50 on a book.
How much birthday money did I receive?
Puzzle Copyright © Kevin Stone
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Answer
£50.
Reasoning
Working backwards:
On Thursday, I had £12.50.
On Wednesday, I had £12.50 x (1 ÷ one half) = £25.
On Tuesday, I had £25 x (1 ÷ two thirds) = £37.50.
On Monday, I had £37.50 x (1 ÷ three quarters) = £50.