Consider a 6-digit number of the form XYXYXY. The number is divisible by :

  1. A. 3 and 7 only
  2. B. 7 and 13 only
  3. C. 3, 13 and 37 only
  4. D. 3, 7, 13 and 37

Correct Answer: D. 3, 7, 13 and 37

Explanation

A number in the form XYXYXY can be written as XY \times 10101. Factoring 10101 yields 3 \times 7 \times 13 \times 37. Thus, it is perfectly divisible by 3, 7, 13, and 37.

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