Multiple choice

Find out the wrong number in the following number series. 2500 1971 1610 1321 1152 1100

  1. 1971

  2. 1610

  3. 1321

  4. 1152

  5. 1100
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E Correct answer
Explanation

The pattern involves subtracting consecutive squares of prime numbers: 23² = 529, 19² = 361, 17² = 289, 13² = 169, 11² = 121. Working backwards: 2500-529=1971, 1971-361=1610, 1610-289=1321, 1321-169=1152, but 1152-52=1100 instead of 1152-121=1031. The last term breaks the pattern, so 1100 is incorrect.

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