What Is the Least Common Multiple (LCM)?
The Least Common Multiple is the smallest positive number that all the numbers in a set divide into evenly. It's commonly used for adding fractions with different denominators and solving scheduling or repeating-pattern problems.
How to Use the LCM Calculator
- Enter two or more numbers, separated by commas.
- View the least common multiple instantly.
How LCM Is Calculated
For more than two numbers, this calculator finds the LCM of the first two, then finds the LCM of that result with the next number, continuing through the full list.
Worked Example
Multiples of 4: 4, 8, 12, 16, 20, 24...
Multiples of 6: 6, 12, 18, 24...
Multiples of 8: 8, 16, 24...
Least common multiple: 24
Common Uses for LCM
- Finding a common denominator when adding or subtracting fractions.
- Scheduling problems (e.g., "when will two repeating events coincide again?").
- Simplifying ratio and proportion problems.
Common Mistakes to Avoid
- Confusing LCM (smallest shared multiple) with GCF (largest shared factor) — they answer opposite questions.
- Listing multiples manually for large numbers instead of using the more efficient GCF-based formula.
Frequently Asked Questions
It's the smallest positive number that all given numbers divide into evenly with no remainder.
Multiply the two numbers together, then divide by their greatest common factor (GCF): LCM(a,b) = (a×b) / GCF(a,b).
To add fractions with different denominators, you need a common denominator — the LCM of the denominators gives the smallest (most efficient) common denominator to use.
LCM (Least Common Multiple) is the smallest number that all given numbers divide into. GCF (Greatest Common Factor) is the largest number that divides into all given numbers — they're inverse concepts.
Yes — this calculator finds the LCM across any number of values by computing the LCM of the first two, then combining that with each subsequent number.