get body Request and return as string

NumbersAPI.js

var Request = require('request');

//doesn't work var Numbers = Numbers || {};

var Numbers = function() {
  // constructor
}

Numbers.prototype = {
  baseUrl : 'http://numbersapi.com/'
  , math: function(integer) {
        console.log('DEBUG: ' + this.baseUrl + integer.toString() + "/math");

        Request(this.baseUrl + integer.toString() + "/math", function(err,res,body) {
          console.log('BODY: ' + body);

          // how do I return body after the callback?
        });
        
        return body (from Request call)
  }
};

exports.Numbers = Numbers;
exports.createNumbers = function() {
  return new Numbers();
}
exports.version = '0.0.1';