Question

31

How to add two big numbers in javascript?

rated 0 times [ 36] [ 5] / answers: 1 / hits: 19685 / 7 Years ago, tue, january 31, 2017, 12:00:00

I have two text boxes. Each will take input up to thousand digits.

Now i want to add these two numbers. My question is what data type should i use to store the result?

I have tried this:

<script>

   var x = 'Thousand digit of number'

    var y = 'Thousand digit of number'

    var z = x + y

</script>

but i am getting result in exponential form. How to store the result and display it?

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marques

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4 Years ago

answered 7 Years ago marisela · Accepted Answer

Input the numbers as string and add each characters each other as array something like this:

 function add() {

        document.getElementById(demo).innerHTML = ;

        var x = document.getElementById(txt1).value;

        var y = document.getElementById(txt2).value;

        var len;

        var lenx = x.length;

        var leny = y.length;

        var x1,y1,rem,div=0;

        if(lenx>leny) len = lenx; else len = leny;



        for(var i=0;i<len;i++){

            if(i>=lenx) x1  = 0;

            else x1 = parseInt(x[lenx-i-1]);

            if(i>=leny) y1 = 0;

            else y1 = parseInt(y[leny-i-1]);

            rem = (x1+y1+div)%10;

            div = Math.floor((x1 + y1+div)/10);

            document.getElementById(demo).innerHTML = rem + document.getElementById(demo).innerHTML;

        }

       if(div>0){

            document.getElementById(demo).innerHTML = div + document.getElementById(demo).innerHTML;

       }

    }

Here the code: https://jsfiddle.net/mtsL1k2x/5/

Note: this is only for natural numbers. You can modify depending on your inputs