ABC26GN1642 · Problems on Numbers
Subject: General Aptitude · Chapter: Problems on Numbers · Exam: · Marks: · Difficulty:
A number consists of two digits. The sum of the digits is 9. If 63 is subtracted from the number, its digits are interchanged. Find the number.
Answer
Explanation
Let the ten’s digit be x. Then, unit’s digit = (9 – x). Number = 10x + (9 – x) = 9x + 9. Number obtained by reversing the digits = 10 (9 – x) + x = 90 – 9x. \ (9x + 9) – 63 = 90 – 9x ⇔ 18x = 144 ⇔ x = 8. So, ten’s digit = 8 and unit’s digit = 1. Hence, the required number is 81.
Explanation as extracted from the printed page; notation may be imperfect.
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