Units and conversions · Grade 7

In Grade 7 you learn: area and volume units.

Metric units are built on 10, 100 and 1,000, so converting between them is just multiplying or dividing. Area and volume units need extra care.

Key facts

  • Mass: 1,000 g = 1 kg, 1,000 kg = 1 tonne. Capacity: 1,000 ml = 1 litre.
  • Area: 1 m² = 100 × 100 = 10,000 cm². Volume: 1 m³ = 1,000,000 cm³.
  • 1 cm³ = 1 ml, so 1,000 cm³ = 1 litre and 1 m³ = 1,000 litres.

Worked examples

Example 1

Change 3.75 km into metres.

Answer: 3,750 m

Example 2

A bag holds 1.2 kg of flour and another holds 450 g of sugar. What is the total mass in grams?

Answer: 1,650 g

Example 3

Change 3.5 m² into cm².

Answer: 35,000 cm²

Example 4

A fish tank measures 60 cm × 30 cm × 40 cm. How many litres does it hold when full?

Answer: 72 litres

Other years