# How do you multiply rational numbers in fraction form?

Dec 23, 2014

You simply multiply the nominators (top) and the denominators (bottom):

a/b * c/d = (a*c)/(b*d

After this, you might have to simplify if asked to do so.
Here's an example:

$\frac{5}{8} \cdot \frac{4}{7}$

Following our rule, we should first multiply the nominators:
$5 \cdot 4 = 20$

After this, we should multiply the denominators:
$8 \cdot 7 = 56$

And then we should divide both these numbers:
$\frac{5}{8} \cdot \frac{4}{7} = \frac{5 \cdot 4}{8 \cdot 7} = \frac{20}{56}$

If you're asked to simplify this answer to the lowest terms, you should divide both the nominator and denominator by 4 (in this case), because that's the GCD of the two numbers.

$\frac{20}{56} = \frac{5}{14}$