When you post a project, it’s helpful if you describe some of the features. And a screenshot or video is really helpful, too.
One suggestion: on most calculators, if you calculate a sum/product/etc. and then press another number, the display clears to show just that number. For example, on your calculator if I press 3 + 6 =, I see 9. But if I then press 1, I see 91 instead of just 1.