Subject: General Aptitude · Chapter: Problems on Numbers · Exam: · Marks: · Difficulty:
In a two-digit number, the digit in the unit’s place is more than twice the digit in ten’s place by 1. If the digits in the unit’s place and the ten’s place are interchanged, difference between the newly formed number and the original number is less than the original number by 1. What is the original number?
(a)25
(b)37
(c)49
(d)52
(e)73
Answer
Answer (as printed): B
Explanation
Let the ten’s digit be x. Then, unit’s digit = 2x + 1. [10x + (2x + 1)] – [{10 (2x + 1) + x} – {10x + (2x + 1)}] = 1 ⇔ (12x + 1) – (9x + 9) = 1 ⇔ 3x = 9 ⇔ x = 3. So, ten’s digit = 3 and unit’s digit = 7. Hence, original number = 37.
Explanation as extracted from the printed page; notation may be imperfect.