Overview
This lecture explains the differences between prime numbers and composite numbers, including their definitions, characteristics, and examples.
Prime Numbers
- A prime number is a whole number greater than 1 that can only be divided by 1 and itself without a remainder.
- The number 2 is the only even prime number because all other even numbers are divisible by 2.
- Examples of prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29.
- 1 is not considered a prime number.
Composite Numbers
- A composite number is a whole number greater than 1 that has factors other than 1 and itself.
- Composite numbers can be divided evenly by numbers other than 1 and themselves.
- Examples of composite numbers: 4, 6, 8, 9, 10.
- 1 is not considered a composite number.
Testing for Prime Numbers
- There is no simple formula to check if a number is prime; check divisibility by all whole numbers less than itself.
- If a number is not divisible by any whole number except 1 and itself, it is prime.
Key Terms & Definitions
- Prime Number — A whole number greater than 1 with exactly two factors: 1 and itself.
- Composite Number — A whole number greater than 1 with more than two factors.
- Factor — A number that divides another number evenly, with no remainder.
Action Items / Next Steps
- Practice identifying prime and composite numbers from a list.
- Try testing divisibility to determine if a number is prime.