Step 5 Objective

Recognise the first few triangular numbers, squares of numbers to at least 12 × 12 and the corresponding roots.

Examples of what pupils should know and be able to do

Probing questions

Two square numbers have a sum of 90.

What are they?

Find the first two square numbers that are also triangular.

Explain how to find the triangular numbers.

What if pupils find this a barrier?

Represent the numbers by dot diagrams or by using interlocking cubes.

Investigate the relationship between square numbers and triangular numbers, using interlocking cubes.

Practise using square and square root keys on a calculator.