When Does It End?

look carefully...........

$6^1=6$

$6^2=36$

$6^3=216$

$6^4=1296$ ........................

.......................

every time the last digit for this case is 6

so, the last digit of $6^{1000} = 6$

every power of 6 ends in 6 so

6^1000 will end in 6 too

All the powers of $6$ ends in $6$ .