CSATNumber System & SeriesDivisibility Divisors and Remainder2017

Certain 3-digit numbers have the following characteristics : 1. All the three digits are different. 2. The number is divisible by 7. 3. The number on reversing the digits is also divisible by 7. How many such 3-digit numbers are there?

A

2

B

4

C

6

D

8

Correct Answer: Option B

Explanation

1. Let the number be 'abc' (value 100a + 10b + c) and its reverse 'cba' (value 100c + 10b + a). Both are divisible by 7. 2. Using the logic of 'Algebraic Representation' [35], the difference between the number and its revers

More Number System & Series PYQs

View all Number System & Series questions →

Master UPSC Revision

Get 10,000+ topic-wise MCQs, spaced repetition, daily CSAT challenges, and detailed performance analytics.

Coming Soon to Play Store
Coming Soon to Play Store