LCM Calculator
Find the Least Common Multiple of two or more numbers instantly — with full step-by-step working shown.
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LCM (Least Common Multiple) is the smallest number that all your numbers divide into evenly. Enter any numbers above and the full working — multiples list, prime factorization, and GCF formula — will appear here automatically.
| Numbers | LCM | Why |
|---|---|---|
| 4, 6 | 12 | 12 is the first number both 4 and 6 reach |
| 3, 5 | 15 | 3 and 5 are co-prime — LCM = 3 × 5 |
| 6, 8 | 24 | GCF = 2 · (6×8)÷2 = 24 |
| 7, 14 | 14 | 14 is a multiple of 7 — LCM = larger |
Frequently Asked Questions
What is the LCM?+
The Least Common Multiple (LCM) is the smallest number that is a multiple of all the numbers you are working with. For example, the LCM of 4 and 6 is 12, because 12 is the smallest number that both 4 and 6 divide into evenly.
What is the difference between LCM and GCF?+
GCF finds the biggest number that divides into your numbers (goes smaller). LCM finds the smallest number your numbers divide into (goes bigger). For 4 and 6: GCF = 2, LCM = 12.
Why is LCM useful?+
LCM is used to add or subtract fractions with different denominators. You find the LCM of the denominators to get the lowest common denominator. It is also used for scheduling problems — like finding when two repeating events happen at the same time.
Can the LCM ever be smaller than the numbers?+
No. The LCM is always greater than or equal to the largest number in your group. If one number is a multiple of the other, the LCM equals the larger number.
What is the LCM of two prime numbers?+
It is always their product. For example, LCM(7, 11) = 77. Since primes share no common factors, they cannot divide into anything smaller than their product.
What is the LCM of a number and 1?+
Always the number itself. Since 1 divides into everything, the smallest number both 1 and N divide into is N.
How are LCM and GCF related?+
They are connected by this formula: LCM(a, b) × GCF(a, b) = a × b. So if you know the GCF, you can always find the LCM by dividing the product by the GCF.
What is the LCM of a number and itself?+
The number itself. For example, LCM(5, 5) = 5, because 5 is already a multiple of 5.