js create 3 digit number code example

Example 1: javascript 1 + "1"

console.log(10+"1"); //101
console.log(10-"1"); //9

Example 2: concantene number in js

Use "" + 5 + 6 to force it to strings. 
This works with numerical variables too:

var a = 5;
var b = 6;
console.log("" + a + b);