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Calculate Power Without Using pow() in Python

Multiply in a loop. Negative exponents: do the positive power, then 1/result.

BeginnerBasic Python ProgramsExample 21 of 25

calculate-power-without-using-pow.py

1# Program to calculate a^b without using pow() or ** for the core logic
2
3base = float(input("Enter the base (a): "))
4exponent = int(input("Enter the exponent (b, integer): "))
5
6result = 1
7
8if exponent >= 0:
9    for _ in range(exponent):
10        result *= base
11else:
12    for _ in range(-exponent):
13        result *= base
14    result = 1 / result
15
16print(f"{base} raised to the power {exponent} is {result}")

Output

Enter the base (a): 2
Enter the exponent (b, integer): 3
2.0 raised to the power 3 is 8.0

In this one

loop multiply, start from 1
negative exponent = 1 / positive power

What's going on

2 ** 3 exists. This loop is so you can see exponentiation is repeated multiply.

result = 1, then multiply by base, exponent times. 2³: 1→2→4→8.

Negative exponent: compute the positive one, then 1 / result. 2⁻³ is 0.125.

^ is still XOR. I will keep saying that until it sticks.

After this program

If the idea is still fuzzy, read Day 1: Introduction to Python in the Python course. For a short check, try the Python quiz (300 questions). Stay with all 25 basic python programs, or see every topic on Python exercises.

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