The remainder of the real number

Question

When I tried this Code:

double d=1.23;
        System.out.println(d%1);

The output was: 0.22999999999999998

My Question is: Why?

Answer 1

The short answer is that double is not accurate. The long answer is to understand that you should learn the way double stored in memory

if you want to do accurate calculations, i would use BigDecimal object of java

    BigDecimal num = new BigDecimal("1.23");
    System.out.println(num.remainder(new BigDecimal(1)));