🚧 Avoid common mistakes · 1 min read
Units, rounding and reading the question
Right working, wrong answer? It is often the units or rounding too early.
Units
Change everything to the same unit before calculating. A room 4 m by 250 cm has area 4 × 2.5 = 10 m2, not 4 × 250 = 1,000.
Remember: 1 m = 100 cm, but 1 m2 = 10,000 cm2 and 1 m3 = 1,000,000 cm3.
Don't round too early
Keep full calculator values until the very end, then round once, as the question asks (e.g. to 2 decimal places or 3 significant figures). Rounding in the middle can change your final answer.
Answer the actual question
If the question asks for the cost 'in naira to the nearest ₦10', or 'the number of full boxes', your final line must answer exactly that.