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Example

Simplifying 123(912)12 - 3(9 - 12)

When an expression contains a parenthesized sub-expression that is multiplied by a factor, the order of operations requires simplifying inside the parentheses before performing the multiplication and any remaining operations:

  1. Parentheses first: Compute 912=39 - 12 = -3 inside the parentheses, giving 123(3)12 - 3(-3).
  2. Multiply: Compute 3(3)=93(-3) = -9 (different signs yield a negative product), giving 12(9)12 - (-9).
  3. Subtract the negative: Subtracting 9-9 is equivalent to adding 99: 12+9=2112 + 9 = 21.

The final result is 2121. A common error is to multiply 3×93 \times 9 or 3×123 \times 12 before resolving the subtraction inside the parentheses. The parentheses override normal left-to-right processing by requiring their contents to be fully evaluated first.

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Updated 2026-04-21

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