Recursive function to multiply two positive numbers

 Algorithm:

1. Display a prompt for the user to enter the first number.
2. Input the first number and store it in variable a.
3. Display a prompt for the user to enter the second number.
4. Input the second number and store it in variable b.
5. Call the recursive multiply(a, b) function: a. If b is 0, return 0 (base case). b. Otherwise, return a + multiply(a, b - 1) (recursive case).
6. Store the result of the recursive function call in variable result.
7. Display the result of the multiplication.

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— Abhin Krishna, S01, EB Department, MEC

Pseudocode:

START
DISPLAY "Enter the first number: "
INPUT a
DISPLAY "Enter the second number: "
INPUT b
CALL multiply(a, b)
FUNCTION multiply(a, b)
    IF b = 0
        RETURN 0
    ELSE
        RETURN a + multiply(a, b - 1)
END FUNCTION
SET result = return value of multiply(a, b)
DISPLAY "The product of", a, "and", b, "is", result
END

Program:

# Recursive function to multiply two numbers
def multiply(a, b):
    # Base case: if one of the numbers is zero
    if b == 0:
        return 0
    # Recursive case: multiply by adding a to the result of multiplying a with (b - 1)
    return a + multiply(a, b - 1)

# Input two numbers
num1 = int(input("Enter the first number: "))
num2 = int(input("Enter the second number: "))

# Calculate the product using recursion
result = multiply(num1, num2)

# Print the result
print(f"The product of {num1} and {num2} is {result}")

Flowchart:

flowchart TD A([Start]) --> B[/Display "Enter the first number:"/] B --> C[/Input a/] C --> D[/Display "Enter the second number:"/] D --> E[/Input b/] E --> F["Call multiply(a, b)"] F --> G{Is b == 0?} G -- Yes --> H[Return 0] G -- No --> I["Return a + multiply(a, b-1)"] I --> J["Store result = return value of multiply(a, b)"] J --> K[/Display "The product of", a, "and", b, "is", result/] K --> L([End])

Important!
If you find any mistakes in my code or flowchart, please comment below this post. I will be happy to correct them and clear up any doubts you may have.