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Difficulty: 3/102023 NMTC 2023 (QII-44)

The remainders when is divided by 7.

Guide / Hint

Hint 1: Find the period of powers of 2 modulo 7. Note that .

Hint 2: Divide the exponent 50 by 3: .

Hint 3: Simplify the expression to .

Solution

Step 1 (Find Cyclicity Modulo 7): We evaluate powers of 2 modulo 7:

  • (This breaks the exponent into cycles of 3).

Step 2 (Exponent Division): We divide the exponent by the cycle period :

Therefore:

Step 3 (Conclusion): The remainder when is divided by 7 is exactly 4.

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