What is H/M/S button in Casio Calculator SL-315TV

SOURCE: Need user manual for Casio sl-200te

To change the tax rate, first press AC. Then press SET % for 2 seconds. Next, press TAX+, then enter the new or current tax rate. Enter the rate for a single digit tax rate such as 5% as 5, a single number; if you have a fractional percentage rate, such as 5.75%, enter it just that way: the 5, then a decimal and followed by 7& 5. Then press SET % again and you're done! I just did it on two of the calculators and it works. Hope this helps!

SOURCE: casio sl - 1100tv % button

It uses an odd notation. For 10 + 50% you need to press 10 [x] 50 [%][+] and it will display 15. For 144 + 60%, you need to press 144 [x] 60 [%] [+] and it will display 230.4 which is the correct answer. Now tell me what the ? key is for because I haven't figured that one out yet,

SOURCE: Looking for manual for Casio calculator SL-210TE

http://www.chung-sim.com/casio.sl.210te.html

SOURCE: Poblem with my CASIO MJ-120T CALCULATOR

Sorry, I could not get a link to the manual for your calculator, but the Casio support FAQ page gives answers to some of your questions.

SOURCE: How change percentage (tax) rate on Casio-1100TV?

FINALLY figured out how to change the tax rate! Press AC. Press and hold the Rate Set (%) button UNTIL THE CURRENT TAX RATE IS DISPLAYED. Enter the new rate you want (such as 7.5). Press the Rate Set (%) button again.