Math Elementary arithmetic Multiplication

# Multiplication

The important rule of multiplication is:

$\text{factor} \cdot \text{factor}$ $=\text{product}$

At multiplication, the operands are designated as factor. The product is the result.

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### The sign

• If both factors have the same sign the product is positive:
$\color{green}{+} \cdot \color{green}{+} = \color{green}{+}$
$\color{red}{-} \cdot \color{red}{-} = \color{green}{+}$

• If the factors have different signs the product is negative:
$\color{green}{+} \cdot \color{red}{-} = \color{red}{-}$
$\color{red}{-} \cdot \color{green}{+} = \color{red}{-}$
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### Mathematical laws

If $a$, $b$ and $c$ are rational numbers, you have to consider these following mathematical laws: