Is 15 a prime? Why?
No, 15 is a composite number since besides 1 and itself, 3 is also one of its factors.
Is 13 a prime? Why?
Yes, 13 is a prime since it only has two factors: 1 and itself.
Is 17 a prime? Why?
Yes, 17 is a prime since it only has two factors: 1 and itself.
Is 21 a prime number? Why?
No, 21 is a composite number since besides 1 and itself, 3 is also one if its factors.
Is 1 a prime number? Why?
1 is NOT a prime number since it only has one factor: itself!
Are all prime odd numbers?
No, 2 is the only even prime number.
Is 18 a prime number? Why?
No, 18 is a composite number since besides 1 and itself, 2 is also one of its factors.
Is 43 a prime number? Why?
Yes, 43 is a prime number as it only has two factors: 1 and itself.
Is 45 a prime number? Why?
No, 45 is a composite number as besides 1 and itself, 5 is also one of its factors.
Is 38 a prime number? Why
No, 38 is a composite number as 38 is an even number, so besides 1 and itself, 2 is also one of its factors.
