Answer:
3^4, or you could say three to the fourth power.
An exponent is a quantity representing the power to which a given number or expression is to be raised, usually expressed as a raised symbol beside the number or expression. 3 x 3 x 3 x 3 is equivalent to 3^4 because you are multiplying three four times.
*Warning: 3 x 3 x 3 x 3 is NOT 3 x 4!!!*