QUESTION

CSAT

Hard

Maths

Prelims 2024

222333+333222222^{333} + 333^{222} is divisible by which of the following numbers ?

Select an option to attempt

Explanation

Step 1: Check divisibility by 2

  • 222 is even, so 222333222^{333} is even.
  • 333 is odd, so 333222333^{222} is odd.
  • The sum of an even number (222333222^{333}) and an odd number (333222333^{222}) is odd.

Thus, 222333+333222222^{333} + 333^{222} is not divisible by 2.

Step 2: Check divisibility by 3 Using the property of divisibility by 3, a number is divisible by 3 if the sum of its digits is divisible by 3.

  • Sum of digits of 222 = 2 + 2 + 2 = 6, so 222 is divisible by 3. Therefore, 222333222^{333} is divisible by 3.
  • Sum of digits of 333 = 3 + 3 + 3 = 9, so 333 is divisible by 3. Therefore, 333222333^{222} is divisible by 3.

Since both terms 222333222^{333} and 333222333^{222} are divisible by 3, their sum is also divisible by 3.

Thus, 222333+333222222^{333} + 333^{222} is divisible by 3.

Step 3: Check divisibility by 37 To check divisibility by 37, use modular arithmetic:

  • 222 mod 37 = 222 - 37 × 6 = 222 - 222 = 0.
    Hence, 222 ≡ 0 mod 37, and 2223330mod37222^{333} \equiv 0 \mod 37.

  • 333 mod 37 = 333 - 37 × 9 = 333 - 333 = 0.
    Hence, 333 ≡ 0 mod 37, and 3332220mod37333^{222} \equiv 0 \mod 37.

Since both terms are divisible by 37, their sum is also divisible by 37.

Thus, 222333+333222222^{333} + 333^{222} is divisible by 37.

Final Answer: The expression 222333+333222222^{333} + 333^{222} is divisible by 3 and 37 but not 2.

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