That's a bit mean. We've all got Internet connected computers and there are loads of online converters* (e.g. https://www.brewersfriend.com/refractometer-calculator/, but I in no way recommend Brewers Friend) or perhaps use a tool for logging and formulating recipes that has a built in converter (I use "Beersmith"). I tried going back to hydrometers recently. Getting a big enough sample out of the fermenter was a pain (deciding whether it's safe to put back is a bigger pain). And trying to read the hydrometer through the murky soup that is fermenting beer was near impossible. And fermenting gas attaches to the hydrometer and distorts the reading. And hydrometers break as soon as look at them. *Online calculators are getting increasingly more complicated as they get tweaked for more and more unimportant accuracy. Just use the "Brix" reading (e.g. ignore "Brewers Friend" "Brix WRI" garbage, it means little more than just plain Brix) and leave any "wort correction factor" at 1 (or default, its sometimes 1.04). For some reason "Brewers Friend" calculates "FG" - ignore that, its not FG its what ever the gravity reading is now.