Find the ones digit of 73^351
Answers.
A) 3
B) 5
C) 6
D) 7
E) 9
The units digit of 73^351 will be the same as the units digit of 3^351   3^1=3 --&gt; the units digit is 3;   3^2=9 --&gt; the units digit is 9;   3^3=27 --&gt; the units digit is 7;   3^4=81 --&gt; the units digit is 1;   3^5=243 --&gt; the units digit is 3 AGAIN;   ...   So, as you can see the units digit repeats in blocks of 4: {3, 9, 7, 1}, {3, 9, 7, 1}, ... Now, since 351=348+3=(multiple of 4)+3, then the units digit of 3^351 will be the third number in the pattern thus 7.   Answer: 7.
<result>D</result>
Find the ones digit of 73^351