Calculator Tools
Find the least common multiple and greatest common factor for two to twenty positive integers. Review each prime factorization and the exact method without floating-point rounding.
Separate 2–20 positive integers with commas or spaces. Each value may be at most 10,000,000,000.
Simple workflow
How to use LCM & GCF Calculator
- 1Enter two or more positive integers separated by commas or spaces.
- 2Select Calculate LCM and GCF.
- 3Review the exact results, every prime factorization and the exponent method.
Good to know
Frequently asked questions
Are GCF and GCD the same?
Yes in this context. Greatest common factor and greatest common divisor both mean the largest positive integer that divides every input exactly.
How many integers can I enter?
Enter 2 to 20 positive integers. Each value is limited to 10,000,000,000 to keep prime-factor work bounded in the browser.
Why are zero and negative values rejected?
This tool uses the common school-arithmetic definition for positive integers. Restricting the domain keeps LCM, GCF and prime-factor steps clear and consistent.
Are large LCM results rounded?
No. GCF and LCM use BigInt integer arithmetic, so a result stays exact even when it is larger than JavaScript's safe Number range.
Practical guide
Find common factors and multiples from exact prime factors
The greatest common factor, also called the greatest common divisor, is the largest positive integer that divides every input. The least common multiple is the smallest positive integer divisible by every input.
Prime factorization makes both results visible: the GCF uses prime powers shared by all values at their lowest exponent, while the LCM uses every needed prime at its highest exponent.
Worked example
Compare 12 and 18
- Start with
- 12, 18.
- Choose
- Select Calculate LCM and GCF.
- You get
- 12 = 2^2 × 3 and 18 = 2 × 3^2, so GCF = 6 and LCM = 36.
Tips for a useful result
- Separate values with commas, spaces or both.
- Use positive whole numbers; decimals, negatives and zero are rejected.
- The input limits bound prime-factor work so an accidental giant value cannot freeze the page.
Exact arithmetic, limits and privacy
The calculator accepts 2 to 20 values, with each value no greater than 10,000,000,000. It uses BigInt arithmetic for GCF and LCM, so the final integer is not rounded through floating-point Number arithmetic.
Values, factors and results stay in page memory and are cleared when you reset or leave the page. They are not transmitted or stored.
Keep going