Whats wrong with this simple 'double' calculation? [duplicate]

Answer 1

d1 - d2 returns the exact result of binary float arithmetic and it is 2.6399999999999997 and so it is printed. If you want to round it, you can do it during printing

System.out.printf("d1 - d2 : %.2f",  d4);

or with Commons-Math

d4 = Precision.round(d4, 2);