Java Android Studio新手，需要一些指导

Question

i'm new here and to Java Android Studio.

Currently i creating an App which functions as below :

1. User key-in a digit for example 1131
2. The App will take 1131 / 80 = 14.1375
3. And the calculation will remove all the front digit which is the 14
4. Use 0.1375 and Times 80
5. Results = 11
6. Then the App will display a certain message for the number 11

So far i'm stuck at the calculation which is For Example :

int x = 1131;
double x1 = x / 80.0;              //Gets 14.1375
double x2 = Math.floor(x1);        //Gets 14.0
double x3 = x1 - x2;               //14.1375 - 14.0 = 0.1374999999999993 ???

something weird shows up during the Math.floor, it suppose to take 14 and execute x1 - x2 ( 14.1375 - 14.0 = 0.1375 )

But instead it shows 0.1374999999999993

Thank you !!

Answer 1

This is because numbers in computer languages are represented by binary. See the answer posted here