Find source from percentage number

Question

Yeah, I might look stupid with this question but Math classes are so long ago for me :).

I need to find the exact number that makes 18.20, 82% off.

So to clarify:

(?) * 0.82 = 18.2

How do i find that number? Thanks!

Answer 1

If 18.20 is 82% off, then 18.20 is 100-82% = 18% of 'some number'.

So we want to know what 100% of this 'some number' is.

So $\frac{100}{18} * 18.2 = 101.11$

Answer 2

$18.20$ is $82$% off of what number $x$?

What number $x$ multiplied by $.82$ yields $18.20$?

Well, $.82 \cdot x=18.20\implies x=18.2/.82 \approx 22.2$

In other words: divide by $.82$

Answer 3

(?) $*\: 0.82 = 18.2$

You divide by $0.82$.

Let $x$ be the number you are looking for.

$x \cdot 0.82 = 18.2$

$\frac{x \cdot 0.82}{0.82} = \frac{18.2}{0.82}$

$\require{cancel}\frac{x \cdot \cancel{0.82}}{\cancel{0.82}} = \frac{18.2}{0.82}$

$$x = \frac{18.2}{0.82} = \frac{910}{41} = 22.1951219512195122$$