I was just thinking, better go back and show my code for anyone else looking to do something similar.
w = document.getElementById('control').value;
document.getElementById('content').style.width = (w + '%');
"Control" represents the HTML5 numberbox.
"Content" is the div to be manipulated.
"w" is the variable and also represents the innerHTML.value of the numberbox.
Works really well.
Thanks for this site, I have learned much here.
Not bragging, I'm far from being a coder but I love the fact that I made my own sites (with help at first) but do about everything I need now.