Subject: General Aptitude · Chapter: Problems on Numbers · Exam: 2009 · Marks: · Difficulty:
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 of the number is 12, then what is the original number?
(a)28
(b)39
(c)82
(d)Cannot be determined
(e)None of these
Answer
Answer (as printed): E
Explanation
Let ten’s digit = x. Then, unit’s digit = (12 – x). \ [10x + (12 – x)] – [10 (12 – x) + x] = 54 ⇔ 18x – 108 = 54 ⇔ 18x = 162 ⇔ x = 9. So, ten’s digit = 9 and unit’s digit = 3. Hence, original number = 93.
Explanation as extracted from the printed page; notation may be imperfect.