TopToolAILCM & GCD Calculator
ⓘ About this tool
🔄 Last updated 21 Sep 2026
✓ Reviewed by TopToolAI Team
Give it two to ten whole numbers and it returns their GCD (also called HCF) and their LCM. The prime factors of each number are listed, so the result is not a black box.
How to use LCM & GCD Calculator
Step-by-step guide to the boxes below. Open it only if you need help.
How to use LCM & GCD Calculator
Step-by-step guide to the boxes below. Open it only if you need help.
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1
Numbers Text box
Enter 2 to 10 positive whole numbers, separated by commas or spaces.
Example: 12, 18, 24
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2
Press “Calculate”
Click the button under the boxes. If something is missing or not valid, a short message tells you which box to fix.
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3
Read your result
Your answer appears under the button, with a short note in plain words where it helps. Change any box and press again to compare different numbers.
LCM & GCD Calculator FAQs
GCD, HCF, GCF: are they different?
No, they are three names for the same thing: the largest number that divides all of yours exactly.
What is the LCM used for in practice?
It is the smallest number that all of yours divide into. That is what you need to add fractions with different denominators, or to work out when repeating events line up.
How do I find the GCD of two numbers?
List their common factors and pick the largest, or use the Euclidean algorithm. The GCD of 12 and 18 is 6.
How do I find the LCM of two numbers?
Find the smallest number both divide into. The LCM of 4 and 6 is 12.
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