I start with 1. Every minute, I double in size. If it takes me 60 minutes to completely fill a glass, how many minutes did it take me to fill half the glass?
59 minutes
Since the size doubles every minute, whatever state the glass is in, one minute prior it was exactly half that size. Therefore, at 59 minutes it was half full.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Easy. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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