Arithmetic error.
PRIMARY 3 · MATHEMATICS
Time
Top 5 mistakes
Ranked by how often they appear across 82 MOE-aligned practice questions in our archive.
Gave seconds in 1 minute, not 2. 1 min = 60 sec, so 2 min = 60 × 2 = 120 sec.
Used the wrong conversion (1 min ≈ 100 sec). 1 minute always equals 60 seconds; 2 × 60 = 120.
Doubled 100 (the wrong conversion) instead of doubling 60. The correct rule is 1 min = 60 sec, so 2 min = 120 sec.
Subtracted 10 min instead of correctly carrying over the hour: did 2:15 + 1:40 = 3:55 by mis-reading 1 h 50 min as 1 h 40 min.
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