It's possible to get far more than 5-10 slits using something called a diffraction grating, which is essentially many closely-spaced slits, repeating over and over again. The one used in this lab has 500 slits per mm. When we use our equation we want d, the distance between slits, which means you will need to invert the 500 lines/mm of your diffraction grating to find d in mm, and then you'll find it useful to convert to nm since your laser is in the nm range