calculating numbers not showing all decimal numbers [duplicate]

I want to know if the PHP has a limit on showing decimal numbers or Do I need to configure something in the PHP config.
I having a project calculating measurement

This is only sample value I used.
In PHP when I calculate this formula.

53 cm / 2.54 inch = 20.866141732283

vice versa

20.866141732283 * 2.54 inc = 52.999999999999

The result is not 53 when I calculate back to cm because It has a missing decimal number. If I calculate it by using the calculator. This is the result

53cm / 2.54 inch = 20.866141732283465

last part 465 is missing in the PHP calculation.

This happened to any number I used.