Find the units digit of 29 79 + 31 81.

9 9 + 1 1 = 81 + 1 = 82, so the units digit is 2.

jmc

number theory junior

Problem

Find the units digit of

29 \cdot 79 + 31 \cdot 81

Solution

9 \cdot 9 + 1 \cdot 1 = 81 + 1 = 82

, so the units digit is

2

Final answer