A = 9, B = - 8, then what are the numbers of 2003 power of a plus 2004 power of B? (it should be 5) please explain the reason

A = 9, B = - 8, then what are the numbers of 2003 power of a plus 2004 power of B? (it should be 5) please explain the reason

You should know: x ^ (4N + k) single digit = x ^ k single digit
(it is the single digit of a ^ 1 = a ^ 5 = a ^ 9...)
The 2003 power of a plus the 2004 power of B
=Single digits of a ^ 3 + B ^ 4
=Single digits of 9 ^ 3 + 8 ^ 4
=Single digit of 9 + 6
=5