6th Grade · The Number System
Greatest Common Factor
6.NS.B.4
Definition
The largest factor that two or more numbers have in common.
Teach it
Where it is taught, with guided notes, practice, homework, an exit ticket and an interactive Teacher Deck.
Examples
- Factors of 12: 1,2,3,4,6,12. Factors of 18: 1,2,3,6,9,18. GCF = 6.
- The common factors of 12 and 18 are 1, 2, 3, 6 — the greatest is 6.
Key rule
Find all common factors, then pick the greatest.
Memory hook
The biggest factor they both share.