PlanetMath: keep-flip-change

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keep-flip-change

(Definition)

Let $a,b,c,d \in \mathbb{Z}-\{0\}$ . A mnemonic device for calculating

$\displaystyle \frac{a}{b} \div \frac{c}{d}$

is KFC. This stands for "keep-flip-change". This means that you keep the first fraction as it is, flip the second fraction, and change the problem to a multiplication problem. Thus, the expression above becomes

$\displaystyle \frac{a}{b} \cdot \frac{d}{c}.$

This yields that

$\displaystyle \frac{a}{b} \div \frac{c}{d}=\frac{a}{b} \cdot \frac{d}{c}=\frac{ad}{bc}.$

"keep-flip-change" is owned by Wkbj79.

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Other names:

KFC, K.F.C.

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Cross-references: expression, multiplication, fraction, mnemonic device

This is version 1 of keep-flip-change, born on 2006-06-13.
Object id is 8023, canonical name is KeepFlipChange.
Accessed 2040 times total.

Classification:

AMS MSC:

97D40 (Mathematics education :: Education and instruction in mathematics :: Teaching methods and classroom techniques. Lesson preparation. Educational principles)

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