Double multiplied by 100 and then cast to long is giving wrong value

Question

I have the following code:

Double i=17.31;
long j=(long) (i*100);
System.out.println(j);

O/P : 1730 //Expected:1731

Answer 1

The double value is represented not as 17.31, but as 17.309999999999999. That's why when you multiply it by 100 you get 1730.99999999999999999. After conversion to Long your double value is truncated towards zero. So you get 1730.