LCM Calculator
Find the Least Common Multiple of two or more numbers — the smallest positive number divisible by all of them.
LCM
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How to use the LCM Calculator
- Enter two or more whole numbers separated by commas.
- Click Calculate.
- Read the least common multiple.
- Use it to add fractions or to find when repeating events coincide.
Formula used
LCM(a, b) = (a × b) ÷ GCD(a, b)
Worked example
Examples
LCM of 12 and 18 = (12 × 18) ÷ 6 = 36
LCM of 4, 6 and 8 = 24
Prime factor method
Write each number as prime factors and take the highest power of each prime. 12 = 2² × 3 and 18 = 2 × 3², so LCM = 2² × 3² = 36. LCM is used to find a common denominator when adding fractions (1/12 + 1/18 = 3/36 + 2/36 = 5/36) and in timing problems: buses every 12 and 18 minutes leave together every 36 minutes.
Tips for accurate results
- LCM is always at least as large as the biggest number.
- For co-prime numbers, LCM is simply their product.
- For several numbers, find the LCM of two, then with the next.
Frequently Asked Questions
LCM is the smallest number all values divide into; GCD is the largest number that divides all values.
24.
It gives the lowest common denominator, keeping numbers small.
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Content reviewed by Vinod, Easy Smart Calculator · Last updated October 2026