Euclid’s Algorithm I

Euclid’s Algorithm allows you to find the HCF of two numbers. The steps of the algorithm are given below:

1. Ask the user for 2 numbers
2. Test which one is bigger
3. Make the bigger number m and the smaller number n
4. Set r to be the remainder when m is divided by n
5. Set n to m
6. Set r to n
7. If r is 0, the HCF is n. Stop
8. Else go back to step 5

This article will cover steps 1 to 3. The first step is to create a script and name it euclid.py.

To write the code for step 1, enter the code shown below into the script:

# Ask the user for the first number
first_number = int(input("Please enter the first number: "))

# Ask the user for the second number
second_number = int(input("Please enter the second number: "))

To test which of the input numbers is bigger, we will use the greater than symbol. We will ignore other cases. The code to do this is shown below:

# Test if the second number is bigger than the first number
if (second_number > first_number):
    # Swap if the first number is greater than the second number
    temp = second_number
    second_number = first_number
    first_number = temp

# Print out to check the swap
print(first_number, second_number)

Now the program can receive input and swap them correctly. Below is an image of a running program.