How to solve
A prime has exactly two positive divisors: 1 and itself. A composite has more than two. The number 1 is neither.
Steps
- Check divisibility by primes up to √n.
- If n has a proper factor other than 1, it is composite.
- Answer neither for 1.
Example
Is 15 prime or composite?
- 15 = 3 × 5.
- More than two positive divisors → composite.
Answer: composite
How to type answers
- Answers: prime, composite, or neither
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