Planetary gear system for practicing math

There was something wrong with the printing profile. I apology for this. Now it is OK. printing profiles are now one for: US, UK, CA, AU, CN, JP, KR and one for DE, AT, CH, NL, RU, BR, AR These small planetary gears are an educational toy. Children can use them to learn and practice multiplication, division, addition, and subtraction in a playful way. Hold the gear in the center and spin the outer ring. Then read the problem and solve it in your head. To check your answer, rotate the gear around the horizontal axis. Now you can verify the result and spin the wheel to select the next problem. In my version, there are two STL files for each spinner: one for the text and one for the gear body, so you can easily color them. The numbers are rotated so that they are always the right way up when selected. The gears are tapered at the top and bottom so you can’t get your fingers caught in the teeth. The symbols for multiplication and division differ in various regions around the world. I have versions for China, Germany, and the USA. There seems to be more consensus on addition and subtraction, so those are only available once.