Let's see this example.
<html>
<body onload="alert((0.1234*300));alert((0.00005*300))"/>
</html>
Why the results are not as should be 37.02 and 0.015 but 37.019999999999996 and 0.015000000000000001 ?
Ps: 0.00005*300 make error while 0.0005*30 and 0.005*3 are ok.
All numbers in JavaScript are represented in binary as IEEE-754 Doubles, which provides an accuracy to about 14 or 15 significant digits. Because they are floating point numbers, they do not always exactly represent real numbers (Source):
console.log(0.1234 * 300); // 37.019999999999996
console.log(0.00005 * 300); // 0.015000000000000001
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