UPSC Prelims 2020·CSAT·Quantitative Aptitude·Number System

A digit n > 3 is divisible by 3 but not divisible by 6. Which one of the following is divisible by 4?

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Last updated 23 May 2026, 3:31 pm IST
  1. A2n
  2. B3n
  3. C2n + 4
  4. D3n + 1Correct

Explanation

First, let's determine the value of n. 1. n is a digit greater than 3: n can be 4, 5, 6, 7, 8, 9. 2. n is divisible by 3: From the above, n can be 6 or 9. 3. n is not divisible by 6: This eliminates n = 6. Therefore, n must be 9. Now, we check which of the options is divisible by 4 with n = 9: A) 2n = 2 * 9 = 18. 18 is not divisible by 4. B) 3n = 3 * 9 = 27. 27 is not divisible by 4. C) 2n + 4 = 2 * 9 + 4 = 18 + 4 = 22. 22 is not divisible by 4. D) 3n + 1 = 3 * 9 + 1 = 27 + 1 = 28. 28 is divisible by 4 (28 / 4 = 7). Thus, option D is divisible by 4.
Quantitative Aptitude: A digit n > 3 is divisible by 3 but not divisible by 6. Which one of the following is divisible by 4?

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