javascript division giving wrong answer? [duplicate]

Question

alert(5.30/0.1);

This gives 52.99999999999999 but should be 53. Can anybody tell how and why?

I want to find that a number is divisible by a given number. Note that one of the number may be a float.

Answer 1

For the same reason that

0.1 * 0.2 //0.020000000000000004

Some decimal numbers can't be represented in IEEE 754, the mathematical representation used by JavaScript. If you want to perform arithmetic with these numbers in your question, it would be better to multiply them until they are whole numbers first, and then divide them.

Answer 2

Scale the numbers to become whole. Then modulus the result.

alert((5.30*10) % (0.1*10));