Standard units and conversions
Edexcel 1MA1 examines unit conversion across both tiers. Foundation tier is mostly direct (mm ↔ cm ↔ m ↔ km), Higher tier embeds conversions inside compound problems (e.g. converting before applying density).
Length
- 10 mm = 1 cm
- 100 cm = 1 m (1000 mm = 1 m)
- 1000 m = 1 km
Mass
- 1000 mg = 1 g
- 1000 g = 1 kg
- 1000 kg = 1 tonne
Capacity / volume
- 1000 ml = 1 litre
- 1 cm³ = 1 ml
- 1000 litres = 1 m³
Time
- 60 seconds = 1 minute
- 60 minutes = 1 hour
- Time is base-60, so adding times needs care: 1h 45m + 0h 30m = 2h 15m, NOT 2h 75m.
Money
- 100 pence = £1
- £4.05 means 4 pounds and 5 pence (NOT 4 pounds 50 pence).
Compound conversions
- m/s to km/h: multiply by 3.6.
- km/h to m/s: divide by 3.6 (or multiply by 5/18).
- g/cm³ to kg/m³: multiply by 1000.
Common Edexcel mark-scheme phrasing
- M1 for a correct conversion factor used.
- M1 for the calculation step.
- A1 for the answer with correct units.
⚠Common mistakes— Common errors
- Time as if it were base-10 (1.5 hours read as 1h 50m).
- Forgetting that £0.5 means 50p, not 5p.
- Mixing units mid-question (cm and m) without converting.
- Using ÷10 between cm and m (it's ÷100).
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