Subtracted separately.
PRIMARY 4 · MATHEMATICS
Fractions
Top 5 mistakes
Ranked by how often they appear across 98 MOE-aligned practice questions in our archive.
Added separately.
Added whole numbers (2 + 1 = 3) and fraction numerators (3 + 7 = 10) to get 3 10/8. Then correctly identified that 10/8 = 1 2/8, extracting the extra whole, but forgot to add 1 to the whole-number part, giving 3 2/8 instead of 4 2/8 = 4 1/4.
Converted 2 3/8 correctly to 19/8, but converted 1 7/8 incorrectly as (1 × 7 + 7)/8 = 14/8 instead of (1 × 8 + 7)/8 = 15/8. Added 19/8 + 14/8 = 33/8 = 4 1/8.
Added whole numbers (2 + 1 = 3) and fraction parts (3/8 + 7/8 = 10/8) correctly, but left the answer as 3 10/8 without converting the improper fraction part 10/8 into a whole number and a proper fraction.
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