what is 99% of 50$

99% = .99    

"of" means  "multiply"   

So we have

.99 * 50  =  $49.50

Yup, CPhill's answer in correct.

Another way you can think of this is with fractions, if it helps you visualize it better.

$$\left({\frac{{\mathtt{99}}}{{\mathtt{100}}}}\right){\mathtt{\,\times\,}}\left({\frac{{\mathtt{50}}}{{\mathtt{1}}}}\right)$$

99/100 is 99%

$${\frac{{\mathtt{4\,950}}}{{\mathtt{100}}}}$$

divide the top and bottom by 100

$${\frac{{\mathtt{49.5}}}{{\mathtt{1}}}}$$

$49.5

You can always, on every number, use: [NUMBER (50) ] / 100 * [PROCENT (99) ], i think.