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Home Aptitude Problems on H.C.F and L.C.M See What Others Are Saying!
  • Question
  • The product of two numbers is 2028 and their H.C.F. is 13. The number of such pairs is:


  • Options
  • A. 1
  • B. 2
  • C. 3
  • D. 4

  • Correct Answer


  • Explanation
    Let the numbers 13 a and 13 b

    Then, 13a x 13b = 2028

    ab = 12.

    Now, the co-primes with product 12 are (1, 12) and (3, 4).

    [Note: Two integers a and b are said to be coprime or relatively prime if they have no common positive factor other than 1 or, equivalently, if their greatest common divisor is 1 ]

    So, the required numbers are (13 x 1, 13 x 12) and (13 x 3, 13 x 4).

    Clearly, there are 2 such pairs.

  • Tags: AIEEE, Bank Exams, CAT, GRE, TOEFL, Bank Clerk, Bank PO, Analyst

    More questions

    • 1. Two numbers A and B are such that the sum of 5% of A and 4% of B is two-third of the sum of 6% of A and 8% of B. Find the ratio of A : B.

    • Options
    • A. 2 : 3
    • B. 1 : 1
    • C. 3 : 4
    • D. 4 : 3
    • Discuss
    • 2. A train 240 m long passes a pole in 24 seconds. How long will it take to pass a platform 650 m long?

    • Options
    • A. 65 sec
    • B. 89 sec
    • C. 100 sec
    • D. 150 sec
    • Discuss
    • 3. What was the day of the week on 17th June, 1998?

    • Options
    • A. Monday
    • B. Tuesday
    • C. Wednesday
    • D. Thursday
    • Discuss
    • 4. The H.C.F. of two numbers is 11 and their L.C.M. is 7700. If one of the numbers is 275, then the other is:

    • Options
    • A. 279
    • B. 283
    • C. 308
    • D. 318
    • Discuss
    • 5. 
      1872/ ? ? = 234

    • Options
    • A. 324
    • B. 64
    • C. 8
    • D. 256
    • Discuss
    • 6. 
      For every 4 leaps taken by a dog, a cat takes 5 leaps in the same time. But distance covered in 3 leaps of dog is same as that of 4 leaps of cat. Then what is the ratio of speed of dog and cat?

    • Options
    • A. 15 : 14
    • B. 16 :15
    • C. 12 :11
    • D. 10 : 9
    • Discuss
    • 7. 
      A come of height 7 cm and base radius 3 cm is curved from a rectangular block of wood 10 cm x 5 cm x 2 cm. The percentage of wood wasted is?

    • Options
    • A. 34%
    • B. 46%
    • C. 54%
    • D. 66%
    • Discuss
    • 8. 
      1, 9, 25, 49, 81,?

    • Options
    • A. 90
    • B. 135
    • C. 121
    • D. 125
    • Discuss
    • 9. 
      An accurate clock shows the time as 3:00 after hour hand has moved 135°, the time would be?

    • Options
    • A. 7:30
    • B. 6:30
    • C. 8:00
    • D. 9:30
    • Discuss
    • 10. 
      P.V. Narsihma Rao was elected party leader on 29th may, 1991. What was the day of the week?

    • Options
    • A. Tuesday
    • B. Friday
    • C. Wednesday
    • D. Sunday
    • Discuss


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