Use simple formulae

What you'll learn

1. 1

   A formula is like a secret code that tells you how to work something out. Imagine a recipe for a cake — you follow the steps to get the cake.

2. 2

   What does a formula help you do?

3. 3

   The formula for the perimeter of a square is P = 4 × s, where s is the side length. Let's work it out for a square with side 5 cm.

4. 4

   Use the formula P = 4 × s to find the perimeter of a square with side 3 cm. Drag the number line to help.

5. 5

   Using P = 4 × s, what is the perimeter of a square with side 7 cm?

6. 6

   Another formula: the area of a rectangle is A = l × w (length × width). Try one with length 6 cm and width 4 cm.

7. 7

   What is the area of a rectangle with length 5 cm and width 3 cm?