Denominator

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Denominator is the name for the bottom part of a fraction. It tells you how many equal parts make up a whole, and is also used in the name of the fraction: "halves", "thirds", "quarters", "fifths", "sixths" and so on. The reduced fraction for a rational must have an integer denominator.

[edit] Example

If we take the fraction: $\frac{2}{3}$ .

3 is the denominator and the name of the fraction is "two thirds" -or, more generally, "two over three". (2 is the numerator.)

[edit] Negative Fractions

In fractions involving negatives, the denominator is made to be positive by convention. Since any factor of -1 can be multiplied out into the numerator, any fraction can be rewritten to have a positive denominator. For example,

$\frac{a}{-b} = 1 \times \frac{a}{-b} = \frac{-1}{-1} \times \frac{a}{-b} = \frac{-1 \times a}{-1 \times -b} = \frac{-a}{b}.$