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s1.5.2

Switching Numbers and Negating on Subtraction

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When a subtraction problem results in a negative answer (e.g., subtracting a larger number from a smaller one), it's often easier to switch the order of the numbers, perform the subtraction, and then negate the result.

This uses the principle ab=(ba)a - b = -(b - a).

For example, to calculate 4561011124\frac{5}{6} - 10\frac{11}{12}, you can instead calculate (101112456)-(10\frac{11}{12} - 4\frac{5}{6}). This simplifies the process by avoiding borrowing across the whole number in a negative context.

(10111241012)=(6112) -(10\frac{11}{12} - 4\frac{10}{12}) = -(6\frac{1}{12}) .

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