Aside from the trivial cubes 0 and 1, only one number in the entire infinite Fibonacci sequence is also a perfect cube. What number is it?
8
The Fibonacci sequence starts 0, 1, 1, 2, 3, 5, 8, 13, 21... The value 8 is 2 cubed. It was proven by J.H.E. Cohn in 1964 that 0, 1, and 8 are the only perfect cubes in the sequence.
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: Medium. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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