What is a standard numeral for exponents?

Answer 1

Typically you will see integers or rational numbers, but any number can be an exponent (especially with growth or decay rate problems). If the exponent is less than zero, then it is the same as putting the number in the denominator (example: 2-1 is the same as 1 divided by 21 and in this case would be 1/2). If the exponent is not an integer, then you will have a root of a number

(example 41/2 is the same as the square root of 4, 81/3 is the same as the cube root of 8)