Question 357250
{{{3^1 = 3 mod10}}},
{{{3^2 = 9 mod10}}},
{{{3^3 = 7 mod10}}},
{{{3^4 = 1 mod10}}}.
{{{3^31 = 3^28*3^3 = (3^4)^7*3^3  =1*7 mod10 = 7 mod 10}}}.
Therefore the remainder is 7.