Word takes care of placing two pages on each physical page printed.
Select the 2 Pages Per Sheet check box.The Margins tab of the Page Setup dialog box.
The first (and easiest) solution is available if you are using Word 2000 or a later version of the program. There are ways around this particular problem, however. Word calculates page numbers based on the physical page, not on some virtual page you may want to set up. The problem comes in when you want to print page numbers on each of your mini-pages. You can easily use Word's column feature to set up your document to print in two columns on the paper, and then cut the paper in half after printing. This is a handy size, as you can get exactly two pages on a landscape-oriented letter-size piece of paper. For instance, you may need a page size of 5 1/2' x 8 1/2' for your document. It is not unusual to need to print information on half sheets of paper.