Mastering Least Common Multiples: 2 Easy Methods for Calculating LCM

Unlocking the Power of Least Common Multiples

When it comes to working with integers, finding the least common multiple (LCM) of two numbers is a crucial operation. But what exactly is the LCM, and how can we calculate it?

The Definition of LCM

The LCM of two integers is the smallest positive integer that is perfectly divisible by both numbers without leaving a remainder. This concept is essential in various mathematical operations, such as fractions, algebra, and number theory.

Calculating LCM Using a While Loop

One way to calculate the LCM of two numbers is by using a while loop and an if statement. Let’s take a look at an example Kotlin program that demonstrates this approach:

kotlin
fun main() {
val n1 = 12
val n2 = 15
var lcm = if (n1 > n2) n1 else n2
while (true) {
if (lcm % n1 == 0 && lcm % n2 == 0) {
println("The LCM of $n1 and $n2 is $lcm")
break
} else {
lcm++
}
}
}


In this program, we initially set the lcm variable to the largest of the two input numbers, since the LCM cannot be less than the largest number. Then, we use an infinite while loop to check if the lcm perfectly divides both numbers. If it does, we’ve found the LCM and can exit the loop. Otherwise, we increment the lcm by 1 and re-test the divisibility condition.

The Alternative: Using GCD to Find LCM

Did you know that you can also calculate the LCM of two numbers using the greatest common divisor (GCD)? The formula is simple:

LCM(a, b) = |a * b| / GCD(a, b)

Let’s see how we can implement this approach in Kotlin:

“`kotlin
fun main() {
val n1 = 12
val n2 = 15
val gcd = gcd(n1, n2)
val lcm = Math.abs(n1 * n2) / gcd
println(“The LCM of $n1 and $n2 is $lcm”)
}

fun gcd(a: Int, b: Int): Int {
if (b == 0) return a
else return gcd(b, a % b)
}
“`

In this example, we first calculate the GCD of the two numbers using a recursive function. Then, we use the formula to calculate the LCM.

The Takeaway

Calculating the LCM of two numbers is a fundamental operation in mathematics, and there are multiple ways to do it. By using a while loop or the GCD formula, you can easily find the LCM of any two integers. Whether you’re working with fractions, algebra, or number theory, mastering the LCM is an essential skill to have in your toolkit.