Lesson 4 of 9
Composites: more than two factors
Show on a big screenCheck the factors of 9: 1, 3, 9. Three factors, not two. A prime has exactly two.
Step 1 of 4
- 9 dots in one row: 1 × 9.
- Regroup into 3 rows of 3: 3 × 3.
- Factors of 9: 1, 3, 9 — composite.
- 1 has only 1 factor — neither.
The rule
A composite has more than two factors. 9 has three: 1, 3, 9. 8 has four: 1, 2, 4, 8.
Watch out!
Odd does not mean prime. 15 has factors 1, 3, 5, 15. Four factors, so 15 is composite. 2 is even, and prime.
1 has only 1 factor: itself. Not two, so not prime. Not more than two, so not composite. 1 is neither.
Slide the number in the lab. Its factor count decides.
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Try the lab to finish this lesson.