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A four digit number 2ab5 is divisible by 25. If the number formed from the two digits ab is a multiple of 13, then ab=

  • A.10
  • B.25
  • C.52
  • D.65

Answer: C

We have given that the number 2ab52ab5 is divisible by 25.

Any number divisible by 25 ends with the last two digits 00, 25, 50, or 75.
So, b5b5 should equal 25 or 75.

Hence, b=2b=2 or 77.
Since aa is now free to take any digit from 0 through 9, abab can have multiple values.

We also have that abab is divisible by 13.
The multiples of 13 are 13,26,39,52,65,7813,26,39,52,65,78 and 491491.

Among these, the only number ending with 2 or 7 is 52.

Hence, ab=52

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