The key to do this is that you must have the file in PowerPoint (extensions are .ppt and .pptx). The Print window in this program allows you to change from printing Slides to Handouts (see red arrow), and then to indicate how many Slides per page (see green box).
If the professor has saved the slide set to another format, try getting the same results by printing multiple Pages per Sheet. This is a printer setting, however. We talk about it in the Save paper by printing double-sided post. You can also request the professor makes the slides available in the original file format.