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Home Aptitude Linear Equation See What Others Are Saying!
  • Question
  • The number obtained by interchanging the two digits of a two-digit number is lesser than the original number by 54. If the sum of the two-digit number is 10, then what is the original number?


  • Options
  • A. 28
  • B. 39
  • C. 82
  • D. cannot be determined

  • Correct Answer
  • 82 

    Explanation

    Let us assume the digits of the original number are unit's digit a and ten's digit b.
    The Original Number will be 10a + b.
    After interchanging the digits the new number will be 10b + a.
    According to question,
    The number obtained by interchanging the two digits of a two-digit number is lesser than the original number by 54.
    New Number = Original Number - 54
    10b + a = 10a + b - 54
    ? 10b + a - 10a - b = -54
    ? 9b - 9a = -54
    ? a - b = 6....................................(1)
    Again according to question,
    Sum of the digits of original number = 10
    a + b = 10..................................................(2)
    Add the equation (1) and (2), we will get
    a - b + a + b = 10 + 6
    2a = 16
    a = 8
    Put the value of a in Equation (2) , we will get
    8 + b = 10
    b = 10 - 8
    b = 2
    Put the value of a and b for original number, we will get
    10a + b = 10 x 8 + 2 = 80 + 2 = 82


  • More questions

    • 1. 
      Five coins are tossed at a time. Then, the probability of obtaining at least one tail is

    • Options
    • A. 31/32
    • B. 1/32
    • C. 1/5
    • D. 5/32
    • Discuss
    • 2. 
      Find the maximum number of tree which can plant 20 m apart on the two side of straight road 1760 m long

    • Options
    • A. 174
    • B. 176
    • C. 180
    • D. 178
    • Discuss
    • 3. 
      1307 x 1307 =?

    • Options
    • A. 1601249
    • B. 1607249
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    • D. 1708249
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    • 4. 
      The circumferences of two concentric are 176 m and 132 m respectively. what is the difference between their radii?

    • Options
    • A. 5 meter
    • B. 7 meter
    • C. 8 meter
    • D. 44 meter
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    • 5. 
      (1/2 ÷ 4 + 20) / (1/2 x 4 + 20) =?

    • Options
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    • B. 23/11
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    • D. 1
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    • 6. 
      Find the cardinal number of the following set {x: x = 2n, n ? N, 4 ? x ? 11}

    • Options
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    • 7. 
      If a fraction is multiplied by itself and then divided by the reciprocal of the same fraction, the result is 18 26/ 27. Find the fraction.

    • Options
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    • 8. 
      (0.04) 3 =?

    • Options
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    • 10. 
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    • Options
    • A. 2400
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