COMMON MISTAKE 1:
Leaving answer in index form even though question does not ask to.
EG: Leaving 216^1/3 as an answer instead of 6
COMMON MISTAKE 2:
Not putting the question into index form, hence getting stuck and being unable to carry on.
EG: 144 = X^2
144 = 12^2
COMMON MISTAKE 3:
Leaving answer in surd or indices form when the question says otherwise.
leaving answer as 3^1/2 when question asks for surd form
leaving answer as Squareroot(3) when question asks for indices form