PHP Program to Find LCM of Two Numbers

Given two numbers, the task is to find the LCM of two numbers using PHP.

Examples:

Input: num1 = 25, num2 = 5
Output: LCM = 25

Input: num1 = 36, num2 = 72
Output: LCM = 72

There are two methods to find the LCM of two numbers, these are:

Using Mathematical Formula

In this section, we use mathematical formula to calculate the LCM of two numbers. The LCM of two numbers is equal to the product of the two numbers divided by their Greatest Common Divisor (GCD).

Example:

PHP

<?php

function findGCD($a, $b) {
    while ($b != 0) {
        $temp = $b;
        $b = $a % $b;
        $a = $temp;
    }
    return $a;
}

function findLCM($a, $b) {

    $gcd = findGCD($a, $b);

    $lcm = ($a * $b) / $gcd;

    return $lcm;
}

$num1 = 12;
$num2 = 18;

echo "LCM : " . findLCM($num1, $num2);

?>

Output

LCM : 36

Using Iteration

In this approach, iteratively checks multiples of the larger number until it finds the first multiple that is also divisible by the smaller number.

Example:

PHP

<?php

function findLCM($a, $b) {
    $max = max($a, $b);
    $min = min($a, $b);

    $multiple = $max;

    while ($multiple % $min != 0) {
        $multiple += $max;
    }

    return $multiple;
}

$num1 = 12;
$num2 = 18;

echo "LCM : " . findLCM($num1, $num2);

?>

Output

LCM : 36