I am using a function where I have a readonly text input, and when I execute the function I want the number value + 1. So let's say I have 60, when I execute the function, the number returned should be 61.

But instead it's coming out 601, which is just adding the number 1 to the string. Any clue as to what is going on? Subtraction, multiplication and division all work fine. Here is a snippet

 var num= $(#originalnum).val() + 1;

 $(#originalnum).val(num);

And yes i've tried a few different variations, am I missing something?