If all they needed was the features of a scientific calculator they would have used their calculator app, it’s pretty clear based on context they’re saying they needed access to a graphing calculator for coursework.

Wabbitemu is an emulator for ti84 and similar graphing calculators

It’s a pretty standard tool to assist with learning any math beyond algebra, and was a requirement in both my uni and high school classes. I’m fortunate enough to have gone to a high school where there were plenty of calculators provided by the school, but the major exams like the SAT and whatnot did not provide one and would also not have allowed phones.

Nope, the wabbit emu is for replacing a TI graphing calculator which is north of ~$150 in the US. Still cheaper than a phone, but only a third or so the price of my daily driver at the time of purchase.

Remember to take your Claritin before starting a sync play session

With certbot there’s probably a plugin to do it automatically, but if you just want to get something working right now you can run the following to manually run a dns challenge against your chosen domain names and get a cert for any specified. This will expire in ~3 months and you’ll need to do it again, so I’d recommend throwing it in a cron job and finding the applicable certbot-dns-dnsprovider plugin that will make it run without your input. Once you have it working you can extract the certs from /etc/letsencrypt/live on most systems. Just be aware that the files there are going to be symlinks so you’ll want to copy them before tarballing them to move other machines.

certbot --preferred-challenges dns --manual certonly -d *.mydomain.tld -d mydomain.tld -d *.local.mydomain.tld