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How many odd numbers which are immediately preceded by perfect cube and followed by perfect square ?

  • A.4
  • B.5
  • C.1
  • D.3

Answer: C

There is 1 such odd number.

Among single digits, the perfect cubes are 1 and 8, and the perfect squares are 1, 4 and 9. An odd digit is needed with a cube just before it and a square just after it.

The only place this happens is 8 3 1 at positions 6, 7 and 8: 3 is odd, 8 before it is a cube (\(2^{3}\)), and 1 after it is a square. Every other odd digit fails on one side, for example the 3 at position 16 has 1 before it but 5 after it.

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