How do you simplify 2.1 div 4.41?

Aug 8, 2016

$= \frac{10}{21}$

Explanation:

$2.1 \div 4.41$
$= \frac{210}{441}$
$= \frac{210}{\left(21\right) \left(21\right)}$
$= \frac{10}{21}$

Aug 8, 2016

$\frac{2.1}{2.1} ^ 2 = \frac{2.1}{2.1 \times 2.1} = \frac{1}{2.1}$

Explanation:

It is very useful to know some of the squares and other powers by heart.

$21 \times 21 = 441$

In this case we could notice that the same numbers are used, just with decimals.

There are 2 decimal places in 4.41 and only one in 2.1

This leads us to realise that $2.1 \times 2.1 = 4.41$

And consequently: $\frac{2.1}{2.1} ^ 2 = \frac{2.1}{2.1 \times 2.1} = \frac{1}{2.1}$