Add multiple floats as well as numbers

addNumber.js

/**
 * Bob Math utilities
 * @author: ducdhm
 * @created: Tue, Feb 11th, 2014 (GTM+7)
 */
(function(Math) {
    /**
     * Find the number of decimal places
     * @method findDec
     * @param {Float|Number} dec
     * @return {Number}
     */
    var findDec = function(dec) {
        dec = '' + dec;

        if (dec.indexOf('.') === -1) {
            return 0;
        } else {
            dec = dec.split('.')[1];
            return dec.length;
        }
    };

    /**
     * Find the greatest number of decimal places
     * @method findFixed
     * @param {Float|Number} dec
     * @return {Number}
     */
    var findFixed = function() {
        var fixed = [];

        for (var i = 0; i < arguments.length; i++) {
            fixed.push(findDec(arguments[i]));
        }

        // log(fixed);

        return Math.max.apply(this, fixed)
    };

    /**
     * Calculate total
     * @method findFixed
     * @param {Float|Number}
     * @return {Float|Number}
     */
    var calculate = function() {
        var total = 0;

        for (var i = 0; i < arguments.length; i++) {
            total += arguments[i];
        }

        return total;
    }

    /**
     * Add float number
     * @method addNumber
     * @param {Float|Number}
     * @return {Float|Number}
     */
    Math.addNumber = function() {
        //Determine the greatest number of decimal places
        var fixed = findFixed.apply(this, arguments);
        var total = calculate.apply(this, arguments);

        //do the math then do a toFixed, could do a toPrecision also
        return +total.toFixed(fixed);
    }

})(Math);