For instance, a microscope that magnifies an image to 40 times its size, would be a 40x microscope.
Your microscope doesn't magnify at all. The image in the lens is the exact same size as the object on the slide. That would make your microscope a 1x microscope. That's not a very powerful microscope.
Your microscope probably isn't very powerful because it's a paper towel roll, painted silver, with the words "microscope" written on the side, in what appears to be crayon.
It's not really a microscope at all.
Which means you probably aren't really a scientist.
Which means your entire Craigslist ad was probably a lie.