Full-fledged practical use, day/time calculation type. This is a CASIO DS-20DC 12-digit calculator. I chose and purchased it based on its performance, but the layout is slightly different from the calculator I used before, so it didn't feel right in my hand. I decided to sell it rather than get used to it. I will wrap it in bubble wrap, put it back in the original box, and ship it via Yu-Packet Post. Thank you.