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GATE 2016 CE (CE2) – Question 5

General Aptitude · Quantitative Aptitude: Algebra, Geometry and Mensuration · 1 mark · Multiple choice

The sum of the digits of a two digit number is 12. If the new number formed by reversing the digits is greater than the original number by 54, find the original number.

  1. 39
  2. 57
  3. 66
  4. 93

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Show answer and explanation

Correct answer: (A) 39

Explanation

Let the tens digit be a and the units digit b. Then a+b=12 and(10b+a)−(10a+b)=54, giving b−a=6. Solving gives a=3,b=9. The original number is **39, A**, and its reversal93 exceeds it by54.