Some free math worksheet sites allow you to choose criteria, click a button, and generate a web page of problems. These types of web sites allow for worksheets that produce random digits in numbers. You should find more robust problems sets on web_generated math worksheets. How can web sites give away math worksheets? Do free math worksheet web sites make money? Yes and no. Let's just say it is very important that you visit and support your favorite free math worksheets web site!
Developers of free math worksheets primarily use either of two methods for displaying and printing worksheets on the Internet. PDF pages require an additional piece of software, Adobe Acrobat, which should automatically open worksheets in your browser. PDF worksheets theoretically cannot be manipulated and display/print precisely as the developer designed. The second mode of delivery, HTML code, displays worksheets directly in your browser window. The downside of using HTML based worksheets is they are prone to printing problems. A worksheet meant for one page can easily bleed over to a second sheet.