Prime and Composite Numbers

TASK

Click the Pen tool, choose Select Object, and double-click the table to edit it. Complete the table and take note of your observations.

Question 1

Which of the following numbers has the most number of factorizations?

9 11 10 12

Question 2

Which of the following numbers has only two factors?

2 7 10 9

Question 3

What do you think is the smallest number of factors of any number? Why?

Discussion

Numbers that have only two factors are called prime numbers. For example, 11 is a prime number because its only factors are 1 and 11. Numbers with more than two factors are called composite numbers. For example, 6 is a composite number because its factors are 1, 2, 3, and 6. The number 1 is a special number. It is not composite and it is not prime.

Question 4

Which of the following are prime numbers?

2 4 3 5

Question 5

Which of the following are composite numbers?

7 8 9 10

Question 6

If we think of prime and composite numbers as areas of rectangles formed by unit squares, which of the following is true about them?

You can only form one rectangle if the number is composite. You can form more than one rectangle if the number is composite. You can form more than one rectangle if the number is prime You can only form one rectangle if the number is prime.