What is the unit digit of 9^77?

💡 Solution & Explanation

The unit digits of powers of 9 repeat in a cycle of 2: 9, 1. Divide the power by 2: 77 ÷ 2 leaves a remainder of 1, which means position 1 in the cycle. So the unit digit of 9^77 is 9. Only the last digit of the base matters for this pattern.