Lesson

We've seen that prime and composite numbers are two types of numbers that can help us with calculations.

The only factors a prime number has is 1 and itself.

Which of the following numbers are prime?

A

10

B

21

C

19

Worked Solution

Idea summary

Every whole number greater than 1 is either a prime number or a composite number

All even numbers greater than 2 are composite numbers

To be a prime number, a number can only have itself and 1 as factors

0 and 1 are not prime or composite numbers

Write down the next square number after 16.

Worked Solution

Idea summary

If we multiply a number by itself, we make a square number. If we use dots to picture this as an array it will make a square shape.

Write down the next 3 triangular numbers.1,\,3,\,6,\,10,\,15,\,⬚,\,⬚,\,⬚

Worked Solution

Idea summary

With triangular numbers, we add 1 more dot to each new row and create a triangle shape with dots.

Identify and describe properties of prime, composite, square and triangular numbers.