Question

find unit digit of 4^1+ 4^2+4^3+........ +4^100​

Answer 1

Answer

0

Step-by-step explanation:

First check unit digits of terms

${4}^{1} = 4 \\ {4}^{2} = 6 \\ {4}^{3} = 4 \\ {4}^{4} = 6 \\ . \\ . \\ {4}^{99} = 4 \\ {4}^{100} = 6$

As you can see single digits will repeat 4 , 6 , 4...

and two consecutive terms's single digit sum is 4+ 6 = 10 , 4+6=10 , .... up to 50times.

But unit digit will be same , 0 .