I'm tried many things but I still have a problem, example: 4.3725 * 350 = 1530.38 but my result is 1530.37 ;/
I tried this:
Number.prototype.round = function(places) {
return +(Math.round(this + "e+" + places) + "e-" + places);
}
and toFixed.
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Do never use string concatenation for arithmetic. This won't work with all numbers. – Bergi Mar 14 '17 at 19:33
1 Answers
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You could use toPrecision(). This returns a string which you can just convert back to a Number and round.
The problem was toFixed() rounds numbers like that: 3.65.toFixed(1) => 3.6
Math.round(): https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/round
Here an example:
function roundTo(number, digits) {
var roundHelp = Math.pow(10, digits); // needed to round to correct number of decimals
number = Number(number.toPrecision(15));
return Math.round(number * roundHelp)/roundHelp;
// if you want the exact number of digits use this return statement:
// return (Math.round(number * roundHelp)/roundHelp).toFixed(digits);
}
var x = roundTo(4.3725 * 350, 2); // x = 1530.38
var y = roundTo(4.2970 * 535, 2); // y = 2298.9
darron614
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Woooow! This is my soultions! Thanks!!! I tried solve this problem by 3hours. Thanks! – Alterwar Jan 29 '17 at 19:03
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Ok, I have a problem. If number 4.2970 * 535 = 2298,90. But my result is 2298,895 ~ 2298,89. Where is the problem? – Alterwar Mar 14 '17 at 19:02
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i updated my answer, the function should now round correct for numbers that end with .5 – darron614 Mar 14 '17 at 19:24
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if u want 2298.90 instead of 2298.9 as result just add another line with .toFixed(digits) – darron614 Mar 14 '17 at 19:29
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You are awesome. What are you doing that js i very simple... Thanks again. – Alterwar Mar 15 '17 at 19:54