Maths : Basic Numeracy

Q 114 / 370

UPSC CSE Prelims 2023

What is the remainder if 2192 is divided by 6?

EXPLANATION

Correct Option (D)

To determine the remainder when 2192 is divided by 6, we can observe the pattern of remainders for successive powers of 2:

  • 21÷6: Remainder = 2
  • 22÷6: 4÷6: Remainder = 4
  • 23÷6: 8÷6: Remainder = 2
  • 24÷6: 16÷6: Remainder = 4

A clear pattern emerges for the remainders: 2, 4, 2, 4, ... This cycle of remainders has a length of 2.

For any integer exponent \(n \ge 1\):

  • If n is odd, the remainder is 2.
  • If n is even, the remainder is 4.

Since the exponent 192 is an even number, the remainder when 2192 is divided by 6 is 4.

Incorrect Options:

The established pattern of remainders for 2n÷6 (for \(n \ge 1\)) is consistently 2 or 4.

  • Option (A) 0: A remainder of 0 would imply that 2192 is perfectly divisible by 6. This is not possible because 2192 is a power of 2 and thus contains only prime factors of 2, whereas 6 requires a prime factor of 3 for divisibility.
  • Option (B) 1: The remainder 1 does not occur in the observed cycle of remainders for powers of 2 divided by 6.
  • Option (C) 2: The remainder 2 occurs when the exponent is odd. Since 192 is an even exponent, 2 is not the correct remainder in this instance.