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Section 15.3 · Geometry and measure

Units of area

Understand the relationships between mm², cm², m², hectares and km², and convert between them.

6 teaching slides 71 practice questions Worked answers for every question

1 · Teaching slidesuse ← → keys

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2 · Key words

square millimetreThe area of a square 1 mm by 1 mm.
square centimetreThe area of a square 1 cm by 1 cm; 100 mm².
square metreThe area of a square 1 m by 1 m; 10 000 cm².
hectareThe area of a square 100 m by 100 m; 10 000 m².
square kilometre1 000 000 m², or 100 hectares.
convertChange from one unit to another.

3 · Summary of the sectionrevise from this

  • An area conversion factor is the square of the length one.
  • 1 cm = 10 mm, so 1 cm² = 100 mm².
  • 1 m = 100 cm, so 1 m² = 10 000 cm².
  • 1 km = 1000 m, so 1 km² = 1 000 000 m².
  • 1 hectare = 10 000 m² — a square 100 m by 100 m.
  • 1 km² = 100 hectares.
  • Big unit → small unit: multiply. Small → big: divide.
  • Choose a unit that keeps the numbers sensible: mm² for a stamp, hectares for a farm.
  • When a shape has mixed units, convert before multiplying.
PDFPrintable worksheet All 71 questions, space to work PDFWorked answers Full solutions, not just the answer

Video lessons1 videos

Converting Metric Units of Area

British corbettmaths

Why the conversion factor is squared: 1 m² is 10 000 cm², not 100.

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4 · Practice71 questions, easiest first

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15.2 Compound shapes
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15.4 Area of a triangle