Python Program for Compound Interest

Let us discuss the formula for compound interest. The formula to calculate compound interest annually is given by: 

A = P(1 + R/100) ^t 
Compound Interest = A - P 

Where, 

• A: amount 
• P: principal amount 
• R: rate 
• T: time span

Using Exponentiation Operator

This example calculates compound interest using the ** (exponent) operator.

P = 1200   
R = 5.4    
T = 2      

A = P * (1 + R/100) ** T
CI = A - P

print("Compound interest:", CI)

Compound interest: 133.0992000000001

Using Built-in pow() Function

Instead of using the ** (exponent) operator, we can also use Python's pow() function.

p = 10000
r = 10.25
t = 5

Amt = p * (pow((1 + r / 100), t))
CI = Amt - p

print("Compound interest:", CI)

Compound interest: 6288.946267774416

Taking Input from User

This method allows the user to enter values at runtime. It uses the same formula but takes user input for principal, rate, and time using the input() function.

p = int(input("Principal amount: "))
r = int(input("Rate of interest: "))
t = int(input("Time in years: "))


Amt = p * (pow((1 + r / 100), t))
CI = Amt - p

print("Compound interest:", CI)

Output

Principal amount: 3000
Rate of interest: 5
Time in years: 3
Compound interest: 472.875

Please refer complete article on Program to find compound interest for more details!

Using for Loop

In this example, we use a for loop to calculate compound interest by repeated multiplications.

p = 1200  
r = 5.4         
t = 2          

Amt = p
for i in range(t):
    Amt = Amt * (1 + r / 100)

CI = Amt - p
print("Compound interest:", CI)