That is correct tertre, but we need a solution.
Like what tertre said, let's cycle through the powers of 3 and 7, and see if there's a pattern.
We have, for the powers of 3: 31=3,32=9,33=27,34=81 . Woah, we found a pattern! The units digit (3,9,7,1), will repeat forever with a power of 3. Since we have to find the units digit of 317 , we can simply do: 174=4R1 . A remainder of 1 , means the first number in the pattern, which is 3 . Next, on to the powers of 7.
We have, for the powers of 7: 71=7,72=49,73=343,74=2401 . We found a pattern here, again! The units digit
(7,9,3,1), will repeat forever with a power of 7. Since we have to find the units digit of 723 , we simply do 234=5R3 . A remainder of 3 means the third number in the pattern, which is 3.
We then have a units digit of 3 for 317 , and a units digit of 3 for 723.
Thus, we have, 3∗3=9
.