Why Double Width = 50/110000; the Output Is 0.000000000000000

Why double width = 50/110000; the output is 0.000000000000000?

Because you're dividing two integers, so it will only take the integer part (integer division).

Dividing integers in a computer program requires special care. Some
programming languages, treat integer division (i.e by giving the integer quotient as the answer). So the answer is an integer.

Examples :

In real life                  In Java

4/3  = 1.33333                4/3  = 1
25/12 = 2.083333              25/12 = 2
9/2 = 4.5                     9/2 = 4
50/110000 = 0.000454545       50/110000 = 0

You can cast one of the number (or both but it's actually useless) to double to avoid that :

double width = (double)50/110000;
double width = 50d/110000;
double width = 50.0/110000;

Java doing Math not as expected

integer/integer will give you the integer value make any value either denominator or numerator as float you will get the answer

int i = (int) Math.ceil((30 * 50) / 1000.0);

                or

int i = (int) Math.ceil((30.0 * 50) / 1000);

                or 

int i = (int) Math.ceil((30 * 50.0) / 1000);

Java divider is giving Zero value

Because all the calculation on the right hand side are of in integer, that is why the result 0.

At least one of the operand should be a floating point number like:

float k= (i * j) / 100.0;

Incorrect 'double' answer when dividing two 'int' number

Because you are doing integer division, which truncates the result to a integer.

You need to convert either one to double.

double k = i / (double)j;

Program not giving expected output

use

 public static void main(String[] args)
{
  float num = (float)145/156;
  System.out.println(num);
}

As, 145/156 is int/int, so result is 0, type casted to float i.e 0.0

No answer being displayed. Any ideas?

You are performing integer division with 20/100, and in Java, dividing ints yields an int, the truncated quotient.

Cast one of them as a double or use double literals to force floating-point division:

((double) 20 / 100)

or

(20.0 / 100.0)

... and similarly you'll need to change (80/100).

Why isn't time calculating correctly?

In the mist of this, I recommend you take a look at Joda Time. It's usually way better to do date math and it takes into consideration often overlooked issues like Timezones, daylight times, etc.

It may be too much, but the jar is small and it will help you with any date/time related operation you have.

Plus it's used by hundreds of apps, so it works.

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