Q1. Find the unit digit of (2517)78
As we see the unit digit of given number is 7 so
71 = 7
72 = 7 * 7 = 4 9
73 = 7 * 9 = 6 3
74 = 7 * 3 = 2 1
75 = 7 * 1 = 0 7
As we see in each multiplication we take the unit digit of previous calculated value and at the power of 5 we see that it repeats from power of 1.
= 78 / 4
= 2
we divide the power with 4 beacuse at the power of 4 we get the different unit digit . and as we see we get the reminder 2.
So 72 = 7 * 7 = 4 9
Unit digit is 9
For the number like (3261)n , (6515)n , (2516)n , (2480)n where unit place digit are 1,5,6,0 respectivelly then unit digit will be same .
