UPSC Prelims 2023·CSAT·Quantitative Aptitude·Number System

What is the remainder if 2¹⁹² is divided by 6?

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Last updated 23 May 2026, 3:31 pm IST
  1. A0
  2. B1
  3. C2
  4. D4Correct

Explanation

To find the remainder when 2^192 is divided by 6, let's look at the pattern of powers of 2 modulo 6: 2^1 = 2 2^2 = 4 2^3 = 8, which is 2 (mod 6) 2^4 = 16, which is 4 (mod 6) 2^5 = 32, which is 2 (mod 6) We observe a pattern: - For n = 1, 2^n mod 6 = 2. - For even n >= 2, 2^n mod 6 = 4. - For odd n >= 3, 2^n mod 6 = 2. The exponent in our question is 192, which is an even number and 192 >= 2. According to the pattern, when the exponent is an even number greater than or equal to 2, the remainder is 4. Therefore, 2^192 divided by 6 leaves a remainder of 4. Analysis of options: A) 0: Incorrect. 2^192 is a power of 2, so it only has prime factors of 2. For it to be divisible by 6, it would need a prime factor of 3, which it does not have. B) 1: Incorrect. Any power of 2 (for n>=1) is an even number. An even number cannot leave a remainder of 1 when divided by an even number like 6. C) 2: Incorrect. This would be the remainder if the exponent were an odd number greater than or equal to 3 (e.g., 2^3 = 8, 8 mod 6 = 2). However, 192 is an even exponent. D) 4: Correct. As per the pattern observed, for an even exponent n >= 2, 2^n mod 6 is 4. The final answer is D.
Quantitative Aptitude: What is the remainder if 2¹⁹² is divided by 6?

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