Foundation Mathematics Primary 3 Addition and Subtraction

Siti uses mental calculation to find 63 + 28. She rounds 28 up to 30, adds 30 to 63, then adjusts. What is 63 + 28?

A 91
B 93
C 81
D 89
Show Worked Solution

Worked Solution

Step 1: Round 28 up to 30 (added 2 extra). Step 2: Add 63 + 30 = 93. Step 3: Subtract the extra 2 to compensate: 93 − 2 = 91. Answer: 91

Correct answer: 91

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