LCM Calculator
Choose a fast answer or optional teaching.
Step-by-step
Practice Mode
Find the least positive number shared by both multiples.
What to understand
The LCM is the smallest positive number that is a multiple of both inputs.
⚡ Smart LCM Shortcuts
Multiple shortcut: If the larger number is already divisible by the smaller number, the larger number is the LCM. Example: LCM(6, 18) = 18.
GCF shortcut: For positive whole numbers, LCM = (first number × second number) ÷ GCF.
When not to use: Listing multiples may be easier for small numbers when a student is first learning what LCM means.
Check: Your LCM must be divisible by both original numbers.