Why is 15 a composite number

Is 15 a Prime Number? Why is 15 not a Prime Number? Factors of 1, 3, 5, 15 Since 15 has more than 2 factors, we can say that 15 is not a prime number. Problem Statements: Is 15 a Prime Number? No Is 15 a Composite Number? Yes Is 15 a Perfect Square? No Multiples of 15 15, 30, 45, 60, 75, 90, , , , Square Root of 15 3.

No Cube Root of 15 2. Composite Numbers Less than Composite Numbers up to Composite Number Definition A composite number is a whole number that can be divided evenly by numbers other than 1 or itself. Example 1: 6 can be divided evenly by 2, so 6 is a composite number.

Example 2: 5 cannot be divided evenly except by 1 and 5 , so is not a composite number it is a so called prime number. Composite numbers chart before Composite numbers chart before Composite numbers list from 1 to Composite numbers list from 1 to Definitions A prime number has only two factors: 1 and itself. To determine if a number is prime or composite, follow these steps: Find all factors of the number. If the number has only two factors, 1 and itself, then it is prime.

If the number has more than two factors, then it is composite. Example 1: Is the number 2 prime or composite? Solution: The factors of 2 are 1 x 2. Example 2: Is the number 9 prime or composite? Solution: The factors of 9 are 1 x 9, 3 x 3. Example 3: Find all prime numbers between 2 and 9. Example 4: Find all prime numbers between 10 and Example 5: Find all prime numbers between 20 and Solution 1: The number 31 is prime because its only factors are one and itself.

Exercises Directions: Read each question below. The prime numbers between 40 and 49 are: 42, 43 and 47 41, 43 and 47 43, 45 and 47 None of the above. The prime numbers between 50 and 59 are: 53 and 59 51 and 59 53 and 57 None of the above. The prime numbers between 60 and 69 are: 63 and 69 61 and 67 60 and 65 None of the above. The prime numbers between 20 and 69 are: 21, 23, 29, 31, 37, 41, 43, 47, 53, 63 and 69 23, 29, 31, 33, 37, 41, 43, 47, 59, 61 and 67 23, 29, 31, 37, 41, 43, 47, 53, 59, 61 and 67 None of the above.

Elementary Math Lessons. Factors and GCF. Multiples and LCM. Primes and Composites. Divisibility Rules. Patterns and Exponents.