Sub-topic 1
2013 · National Preliminary
Free
Inserting parentheses to make $3+5^2-8\times3+5=0$ true
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Sub-topic 2
2013 · National Preliminary
Premium
Is $5\times7-3+3\times5+3=44$ when grouped as $5\times(7-3)+3\times(5+3)$?
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Sub-topic 3
2013 · National Preliminary
Premium
Is $2\times5-\tfrac{1}{2}\times10\times9=45$ when grouped as $(2\times5-\tfrac{1}{2}\times10)\times9$?
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