Computed 3 × 250 = 750, then divided by 300 instead of 1000 when converting grams to kilograms. The conversion factor is 1 kg = 1000 g, not 300 g.
PRIMARY 5 · MATHEMATICS
Length and Mass
Top 5 mistakes
Ranked by how often they appear across 13 MOE-aligned practice questions in our archive.
Multiplied 3 × 250 = 750 correctly but wrote the answer as 750 kg without converting grams to kilograms. Remember: 1 kg = 1000 g, so divide by 1000.
Converted one packet correctly (250 ÷ 1000 = 0.25 kg) but forgot to multiply by the number of packets. The total mass covers all 3 packets.
Calculated correctly as 4 m 10 cm = 410 cm, but forgot to include the 10 cm remainder when converting back from centimetres to metres.
Subtracted the cut length (1 m 80 cm) from only the first piece (3.5 m − 1 m 80 cm = 1 m 70 cm), then forgot to add back the second piece (240 cm).
Want to fix these mistakes for your child?
Superholic Lab's quiz engine flags every misconception by name and routes your child to targeted practice in our 3-day Plan Quest. Free 7-day trial.
Start a free 7-day trial →