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Problem of the day 16.7.09

with 10 comments


What is the sum of the digits of a two digit number which is 32 less than the square of the product of its digits?

A. 12                   B. 11                 C. 10 .                     D. 9                           E.      8

Written by Implex

July 16, 2009 at 5:28 am

10 Responses

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  1. 8

    anonymous

    July 16, 2009 at 8:27 am

  2. I got the same by trial & error.. trying dif combs till i got the answer as 17 .
    Could you please elaborate the method that you might have used ?

    Hari

    July 16, 2009 at 8:39 am

  3. I started with 36-32=4 not works
    49-32=17 which is 7^2
    so we r done..

    it can be done algebraically, but its a bit tedious

    Rahul

    July 16, 2009 at 8:48 am

  4. answer : 17

    Method : tens place cannot be 2 since after 24 the differences hugely . so tens place has to be one and becomes quite apparent that it has among 15,16,17, 18 .

    nikhil

    July 16, 2009 at 11:50 am

  5. Nice, Nikhil

    Rahul

    July 16, 2009 at 1:38 pm

  6. 8

    kuldeep

    July 20, 2009 at 1:11 pm

  7. method
    max possible number 99+32=131 and minimum is 10+32=42
    we have to watch for squares b/w them.
    we are left with 36/49/64/81

    (1×7)^2=49 =>49-32=17

    shivam

    July 24, 2009 at 8:30 am

    • hai shivam , yours approach is excellent

      rahul

      July 25, 2009 at 2:51 pm

  8. i started out wit 12 but due to huge diff. shifted directly 2 option e and gotten the ans by trial n error… bt i suppose its a bit stupid coz its tym consuming… it ws nice anyways.

    Aakash

    August 11, 2009 at 11:16 am


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