What is the units digit of the solution to 177^28−133^23? Choices.
A) 1
B) 3
C) 4
D) 6
E) 9
Let's reduce the clutter and make it easy to solve   So, 7^28 - 3^23 will have the same units digit as the big numbers above   Both 7 and 3 have a cyclicity of 4, i.e. their powers repeat the units digit after every 4th power   So , 7^28 has the same units digit as 7^4 ,which is 1   Similarly, 3^23 has the same units digit as 3^3, which is 7   Now, we get   xx...xx1 - xx....xx7 = xx...xx4   Thus, the units digit of the solution to 177^28 - 133^23 is 4   4orrect Option : 4
<result>C</result>
What is the units digit of the solution to 177^28−133^23?