What is the ones digit in the number 3^2086?

3 9 27 81    3^5 = 243

3^6 = 243*3 = 729

 

So the units digiit appears to cycle  in this roup of 4:      3   9   7   1       3  9  7  1  

2086/4 = 2086/4 = 521  R 2          so units digit will be   9