Least Common Multiple (LCM) Calculator
How to Calculate LCM
The Least Common Multiple (LCM) is the smallest positive integer that is perfectly divisible by a set of numbers without leaving a remainder. It is a fundamental concept in arithmetic and algebra, often used when adding or subtracting fractions with different denominators.
Method 1: Listing Multiples
This is the most straightforward method for small numbers. You list the multiples of each number until you find the first one they all share.
Multiples of 4: 4, 8, 12, 16, 20…
Multiples of 6: 6, 12, 18, 24…
LCM = 12 (The first number to appear in both lists).
Method 2: Prime Factorization
For larger numbers, prime factorization is more efficient. You break each number down into its prime factors and then multiply the highest power of every prime factor present in any of the numbers.
12 = 22 × 31
18 = 21 × 32
Highest power of 2: 22 = 4
Highest power of 3: 32 = 9
LCM = 4 × 9 = 36
Method 3: Using the GCD Formula
There is a specific mathematical relationship between the Greatest Common Divisor (GCD) and the LCM of two numbers:
LCM(a, b) = (a × b) / GCD(a, b)