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Python Program to Calculate the Power of a Number

Beginner · Numbers

The power of a number, written base^exponent, means multiplying the base by itself exponent times: 2^5 = 2 x 2 x 2 x 2 x 2 = 32. This program works out a power with a loop and checks it against Python's built-in ways.

Program

power_of_a_number.py
base = 3 # or: base = int(input("Enter the base: "))
exponent = 4 # or: exponent = int(input("Enter the exponent: "))
result = 1
for i in range(exponent):
result *= base # multiply by the base once per step
print(f"{base} to the power {exponent} = {result}")
print(f"Using the ** operator: {base ** exponent}")
print(f"Using pow(): {pow(base, exponent)}")
Output
3 to the power 4 = 81
Using the ** operator: 81
Using pow(): 81

How it works

  1. result starts at 1, because multiplying by 1 changes nothing and any number to the power 0 is 1.
  2. The loop runs exponent times and multiplies result by base each time: 3, 9, 27, 81.
  3. base ** exponent is the power operator, and pow(base, exponent) is the same as a function.
  4. The loop only handles whole exponents of 0 or more, while ** also works with negative and decimal exponents.

Other ways to write it

Using recursion

Using recursion
def power(base, exponent):
if exponent == 0:
return 1
return base * power(base, exponent - 1)
print("2^10 =", power(2, 10))
print("5^3 =", power(5, 3))
Output
2^10 = 1024
5^3 = 125

Each call multiplies by the base once and asks for a power one lower, until the exponent reaches 0.

Negative and decimal exponents

Negative and decimal exponents
import math
print("2 ** -2 =", 2 ** -2)
print("8 ** (1/3) =", 8 ** (1 / 3))
print("math.pow(2, 10) =", math.pow(2, 10))
print("pow(2, 10, 1000) =", pow(2, 10, 1000))
Output
2 ** -2 = 0.25
8 ** (1/3) = 2.0
math.pow(2, 10) = 1024.0
pow(2, 10, 1000) = 24

A negative exponent gives a fraction and 1/3 gives a cube root. math.pow() always returns a decimal, and pow() with a third number gives the remainder of the power, which is used in cryptography.

Try it yourself

Print the powers of 2 from 2^0 up to 2^10 in a loop.

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