As a math aficionado, I absolutely adore these. In fact, I just ordered 3 more sets! These are fun to wear with a matte top coat since they give a chalk-board appearance that way. I love that they glow in the dark, too, since it adds a bit of fun. Did you know that the Fibonacci series is a good approximation for converting miles into kilometers? 1, 1, 2, 3, 5, 7, 12, 19, 31: 1 mile is about 2 km, 3 miles is about 5 km, 7 miles is about 12 km, 19 miles is about 31 km, and so on... it's not perfect, but it sure is useful to have a quick reference on your nails!