CAT , GMAT , GRE , MBA
If m is a positive integer, a x a x a ... m times is written as a^m. a is called the base and m is the power. We read it as "a to the power m".
The power is also called "the index" or "the exponent".
The surd notation is another way of expressing fractional indices. It also means the roots of a number. In other words an irrational root of a positive rational number is called a surd.
Some basics on this topic