LCM Calculator
Enter two or more numbers and get the LCM instantly. Everything runs on your device - nothing is ever uploaded.
Runs entirely on your device - nothing is ever uploaded.
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How to use the LCM Calculator
- Type two or more whole numbers, separated by commas.
- Read the least common multiple - the smallest number every input divides into.
- Use it to align fraction denominators or sync repeating schedules.
What it is for
Finding when repeating cycles coincide - buses every 12 and 18 minutes meet every 36 - and building common denominators for adding fractions. Anytime the question is when things next line up, the answer is the LCM.
How it works
The LCM is computed through the GCF: LCM(a, b) = a × b ÷ GCF(a, b), with the GCF itself from the Euclidean algorithm. Results fold across every number you enter and stay exact up to 15 digits.
What is the least common multiple
The LCM is the smallest number every input divides into. For 12 and 18, listing multiples gives 12, 24, 36... and 18, 36..., so the LCM is 36. Faster is prime factorization: 12 = 2² × 3 and 18 = 2 × 3², and the LCM takes each prime at its highest power: 2² × 3² = 36. Two bus routes repeating every 12 and 18 minutes next coincide 36 minutes out.
Common denominators need the LCM
Adding fractions with different bottoms is the LCM's home turf: for 5/12 + 7/18, the LCM of 12 and 18 is 36, so the sum becomes 15/36 + 14/36 = 29/36. Using the least common multiple instead of multiplying denominators keeps numbers small and usually lands already simplified.