In this worksheet, we will practice identifying prime and composite numbers and differentiating between them.
Is 21 a prime or a composite number?
- A a composite number
- B a prime number
Is 23 a prime or a composite number?
- A a prime number
- B a composite number
All prime numbers are odd except .
Determine whether the number 85 is prime, composite, or neither.
- Aneither prime nor composite
Fady is learning about prime numbers. He knows that 5 is a prime number, because the only factors of 5 are 1 and 5.
Is 9 a prime number? Why?
- A No, because 3 is a factor.
- B Yes, because its only factors are 1 and 9.
Maged says that 1 is a prime number because it only has 1 factor pair.
Is he correct? Why?
- A No, because all odd numbers are prime.
- B Yes, 1 only has one factor.
- C Yes, because all odd numbers are prime.
- D No, prime numbers have two factors, 1 only has one factor.
- ENo, prime numbers have more than two factors, 1 only has one factor.
Mariam says that every even number is composite because 2 is a factor.
Is she correct? Why?
- A Yes, because all odd numbers are prime.
- B Yes, because 2 is an even number.
- C Yes, because 2 is even and composite.
- D No, because 2 is even and prime.
- E No, because 2 is even and composite.
A teacher asked her class to colour all the prime numbers between 1 and 10. Here are some of their answers. Which one is correct?
Nada bought these four raffle tickets, and one of them was the winning ticket.
- A ticket number 34
- B ticket number 15
- C ticket number 23
- D ticket number 17
- Eticket number 18
Which of the following is a prime number?
- A 4
- B 8
- C 45
- D 43
Is 96 a prime number?
Are the numbers 2, 47, and 79 prime numbers?
Which of the following is not a prime number?
Find a prime number between 37 and 46.
Look at these numbers.
How many of these numbers are prime?
Which is the largest prime number?
Which is the smallest composite number?
State two prime numbers that are greater than 15 and less than 95.
- A45, 61
- B44, 60
- C42, 58
- D43, 59
All odd numbers greater than 7 can be expressed as the sum of three prime numbers. Which three prime numbers have a sum of 97?
- A17, 18, 62
- B16, 20, 61
- C18, 19, 60
- D17, 19, 61
Find the smallest prime number that is greater than 40.
Which of the following integer sequences is not guaranteed to have infinitely many primes?
How many prime numbers have integers as their square roots?
How many prime numbers are there, and why?
- AWe do not know, because computers are not powerful enough to compute as largely as we need.
- BFinitely many, because once you reach a certain size, every number factors into smaller primes.
- CInfinitely many in theory, as you could theoretically extend the sieve of Eratosthenes indefinitely.
- DInfinitely many, otherwise you could simply take the product of all of them and add one.