How to round fractional value in JavaScript properly

Question

How to round the factorial value in java scripts if we have below value

7.156945704626378 e +118

I want 7.16 only please let me know if we have any solution?

If you exclude the exponent value, the representation value might change — Arun P Johny, Jan 13 '14 at 08:32
`7.156945704626378e118` = `715694570462637800000000000000...000.00`. What exactly do you mean by "I want _7.16_"? — Salman A, Jan 13 '14 at 08:40

Igl3 · Answer 1 · 2014-01-13T08:40:26.387

0

Put it in a String variable:

var x = "7.156945704626378e+118";

Then use a regular expresion which checks for the part before e and parse it back to float:

var y = parseFloat(x.match(/\d+[.][0-9]+/)[0]);

And round to 2 decimal points by:

var z = y.toFixed(2);

If you still want your e118 just multiply z with 1e118 then.

edited Jan 13 '14 at 08:40

answered Jan 13 '14 at 08:32

Igl3

score 0 · Answer 2 · edited May 23 '17 at 12:29

0

((Number(7.156945704626378e+118))/1.0e+118).toFixed(2);

try this

you can refer links

and

edited May 23 '17 at 12:29

Community

answered Jan 13 '14 at 08:33

`7.156945704626378e+118` is already a number, why do you need to convert it to a number explicitly? And if you do, you have to use `Number()`. – Barmar Jan 13 '14 at 08:36
Actully its a scirntific number.. to convert it to actual number we need to use `number` here – The Hungry Dictator Jan 13 '14 at 08:37
It's still `Number`, capital `N`, and don't think this would work ? – adeneo Jan 13 '14 at 08:39

score 0 · Answer 3 · answered Jan 13 '14 at 08:33

0

var number=7.1569;
number*=100;
var new_number = Math.round(number);
new_number/=100;

answered Jan 13 '14 at 08:33

Moussawi7

score 0 · Answer 4 · answered Jan 13 '14 at 08:53

I am not sure whether this approach is correct but this give what user want in question.

Number((+num.toString().replace(/e.*/, '')).toFixed(2))

DEMO

var num = 7.156945704626378e+118;
console.log(Number((+num.toString().replace(/e.*/, '')).toFixed(2)));

# 7.16

Note: This assumes that exponent is not significant and mantissa is what all required for rounding off.

4 Answers4