Question

How do you convert $100$ millimeters to meters?

Answer 1

$100mm=0.1m$
Let $x$ represent unknown count of meters
Know : $1000$ milimetres $\left(mm\right)=1$ metre $\left(m\right)$
Using the method of ratios :
$\frac{meters}{millimetres}\to \frac{m}{mm}=\frac{1}{1000}$
So we need to solve for :
$\frac{m}{mm}=\frac{1}{1000}\equiv \frac{x}{100}$
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Note:
In ratio, for multiply or divide, what you do to the bottom you do to the top.
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We need to change $1000$ into $100$
$\Rightarrow \frac{m}{mm}\equiv \frac{1÷10}{1000÷10}\equiv \frac{x}{100}$
$\Rightarrow \frac{m}{mm}=\frac{0.1}{100}=\frac{x}{100}$