How do you program precentege

Question

I want to calculate some numbers and i cant seem to get it to work the calculation im trying to do is

Example 2.548% * (1 - 2.657%) = answer in percent

Answer 1

1% = 0.01, your example:

0.02548 * (1 - 0.02657) = 0.0248029964
0.0248029964 *100 = 2.48029964
result: 2.48029964%

Answer 2

Oooh ok its that simple but if we say i have a

Double nr1 = 5.45;
Int nr2 =1;
Double nr3 = 1.6544;
Double result;

result = nr1 * (nr2 - nr3);

How do i convert them to 0.0545 from 5.45? If the Double has that value in the beginning?