Learn the 3-Step Method
1See the rows of squares.
A 8 × 5 rectangle holds 5 rows of 8 unit squares.
2Multiply length × width.
8 × 5 = 40 — no counting needed.
3Use square units.
Area is measured in cm², m², km² — the ² matters.
Worked Example
A rectangular rug is 3 m long and 2 m wide. What is its area — and what does carpeting it cost at £15 per m²?
Watch Out! Common Mistakes
Wrong! Adding gives half the perimeter. Area MULTIPLIES: 8 × 5 = 40 cm².
Wrong unit! Area is measured in cm² — the little ² shows it’s squares, not length.
Wrong! Same units first: 100 cm × 50 cm = 5000 cm² (= 0.5 m²).
⬇ Cheat Sheet
- Area of a rectangle = length × width.
- Answer in square units: cm², m².
- Same units before multiplying.
- Square: area = side × side.
📖 Continue Your Journey
Quick summary
- Area = length × width for any rectangle.
- The answer is in square units: cm², m².
- The formula is just fast square-counting: 5 rows of 8 squares = 40.
- Make units match before multiplying.
Frequently asked questions
What is the formula for the area of a rectangle?
Length × width. An 8 cm by 5 cm rectangle has an area of 40 cm².
Why is area measured in square centimetres?
Because area counts how many 1 cm × 1 cm squares fit inside the shape — the ² records that we're counting squares, not lengths.
What real problems use area?
Carpets, painting walls, gardening, wrapping paper — usually paired with a cost per square metre, as in this lesson's worked example.
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