http://kfgw55ndxkdnxu42cntbm3fd7tthrxgruq4bewaxhc7iytysetmreuyd.onion/blogs/20231120_blog.html
I’d recommend a vintage calculator, preferably with lit LED numbers. Anything from the 70’s and 80’s would make a perfect choice. These are also pretty darn affordable. A calculator watch would be killer too! For anyone living outside the US, these calculators will likely follow an order of operation that might not be expected by the rest of the world.