Not digit addition.
PRIMARY 3 · MATHEMATICS
Length and Mass
Top 5 mistakes
Ranked by how often they appear across 30 MOE-aligned practice questions in our archive.
Forgot to convert 1 km into 1000 m and used only the 250 m part: 250 + 800 = 1050 m.
Added 1000 m for the 1 km but dropped the 250 m: 1000 + 800 = 1800, then mis-added an extra 50 to get 1850.
Converted 1 km 250 m correctly to 1250 m, but wrongly converted 800 m into 8000 m (treated each m as 10 m): 1250 + 8000 = 9250 m.
You added 250 + 875 wrongly. Re-check: 250 + 875 = 1125, not 1025.
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