In this article, we will learn about python program to subtract two numbers using recursion with examples.

Getting Started

The task is to subtract two numbers in python using recursion. For example,

If x = 10 and y = 5, then output is 10 – 5 = 5.

Method 1: Using Static Input

Pseudo Algorithm:

• Define a function that accepts parameter x and y.
• Call this function recursively with x-1 and y-1 until y becomes 0.
• Return the value of x when y is 0.

Basically we are decreasing value of x and y together by 1 until y becomes zero. In this way, we are decreasing value of x by y.

 
def subtract(x, y):
    if(y == 0):
        return x
    else:
        return subtract(x - 1, y - 1)


a = 658
b = 640

result = subtract(a, b)
print("Result:", result)

Output:

 
Result: 18

Method 2: Using User Input

In below program, we took input from user using input() method. Then, type casted into integer using int.

 
def subtract(x, y):
    if(y == 0):
        return x
    else:
        return subtract(x - 1, y - 1)


x = int(input("Enter a number"))
y = int(input("Enter another number"))

result = subtract(x, y)
print("Result:", result)

Output:

 
Enter a number
12
Enter another number
2
Result: 10

That’s how we can write python program to subtract two numbers using recursion.

Reference: Subtraction

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