# Least common multiple

What is the LCM of two numbers?

The lowest common multiple (LCM) is the lowest multiple shared by two or more numbers. For example, for the numbers 2 and 5, the lowest common multiple is 10 – the number both numbers can multiply into without a remainder.

## Make

Write a program that outputs the LCM of two numbers input.

Use this boilerplate code as a starting point:

### Success Criteria

Remember to add a comment before a subprogram, selection or iteration statement to explain its purpose.

#### Create a subprogram called `lcm` that:

1. Takes two parameters: number1 and number2.
2. Starts a counter at the highest of the two numbers.
3. Counts up until the counter is divisible by both numbers with no remainder.
4. Returns the counter.

#### Complete the `main program` so that:

1. The user can input two numbers.
2. The result is calculated by calling the subprogram lcm.
3. The result is output in the format: “The LCM of {number1} and {number2} is {result}”.

#### Typical inputs and outputs from the program would be:

Enter the first number: 2

Enter the second number: 5

The lcd of 2 and 5 is 10.

Enter the first number: 6

Enter the second number: 4

The LCM of 6 and 4 is 12.

Enter the first number: 7

Enter the second number: 40

The LCM of 7 and 40 is 280.

Enter the first number: 2

Enter the second number: 10

The LCM of 2 and 10 is 10.

#### Knowledge Organiser

Use these resources as a reference to help you meet the success criteria.

## Evaluate

Run the unit tests below to check that your program has met the success criteria.

Enter the first number: 2

Enter the second number: 4

The LCM of 2 and 4 is 4.

Enter the first number: 8

Enter the second number: 8

The LCM of 8 and 8 is 8.

Enter the first number: 6

Enter the second number: 4

The LCM of 6 and 4 is 12.

Enter the first number: 8

Enter the second number: 10

The LCM of 8 and 10 is 40.

Enter the first number: 16

Enter the second number: 72

The LCM of 16 and 72 is 144.

Check that you have:

• Used comments within the code to describe the purpose of subprograms, conditions and iterations.
• Used meaningful identifier names. That means the names of subprograms and variables indicate what they are for.

Craig ‘n’ Dave

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