Least Common Multiple Calculator
Find the least common multiple, or LCM, of two or more positive whole numbers.
Least Common Multiple Calculator
Enter two or more positive whole numbers separated by commas, spaces, or semicolons.
How it works
Formula and steps
The formula shows how the least common multiple calculator turns your inputs into the result. Use it to check the calculation, then follow the example steps to see each part of the math.
Formula & steps
Least common multiple formula
LCM(a, b) = |a x b| / GCF(a, b)
Use this for two positive whole numbers.
LCM(a, b)= Least common multiple of a and ba, b= Input numbersGCF(a, b)= Greatest common factor of a and b|a x b|= Absolute value of the product- 1Enter two or more positive whole numbers.
- 2Find prime factors for each number.
- 3Use the highest needed powers of each prime factor.
- 4Multiply those factors to get the least common multiple.
Worked examples
The least common multiple of 12 and 18 is 36.
The least common multiple of 8, 9, and 21 is 504.
Common uses
- LCM calculator
- Least common multiple calculator
- Common multiple calculator
- Lowest common multiple
- Common denominator problems
Common mistakes
- Confusing the least common multiple with the greatest common factor.
- Stopping at any common multiple instead of the smallest positive common multiple.
- Using decimal or negative inputs when the calculator expects positive whole numbers.
LCM guide
How to find the least common multiple
The least common multiple, or LCM, is the smallest positive whole number that all entered numbers divide into evenly. It is also sometimes called the lowest common multiple.
LCM calculator
Enter two or more positive whole numbers. The calculator finds the common multiple using GCF and prime-factor relationships, then shows the result with steps.
LCM and common denominators
When fractions have different denominators, the LCM of those denominators is the least common denominator.
LCM calculator names
People also search for this as an LCM calculator, common multiple calculator, or lowest common multiple calculator. These names usually refer to the same number: the smallest positive multiple shared by every input.
FAQ
The least common multiple is the smallest positive whole number that is a multiple of each input number.
Yes. Lowest common multiple and least common multiple are common names for the same idea.
For fractions, the LCM of the denominators is the least common denominator.
No. This calculator supports positive whole numbers only, not variables, monomials, or polynomials.
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