What is the remainder when 7^10 is divided by 5?

✓ Correct Answer: Option D

Examine the pattern of remainders of powers of 7 when divided by 5: 7^1 mod 5 = 2. 7^2 mod 5 = 49 mod 5 = 4. 7^3 mod 5 = 343 mod 5 = 3. 7^4 mod 5 = 2401 mod 5 = 1. The cycle of remainders is (2, 4, 3, 1), with length 4. To find 7^10 mod 5, find 10 mod 4 = 2. So the remainder is the same as for 7^2, which is 4.