ok, so I bought an used HP 12C calculator from Amazon. Since I just finished SS 16, this calculator is driving me crazy! it can’t calculate the YTM properly. First of all, when I turn it on, it displays a “c” right on top of CHS and I can’t get rid of it, maybe the “c” is causing the error. Let me give you an example: FV=1000 PMT=100 N=10 PV=-800 according to Schwesser, YTM should be 13.8 but I get 15.65. This is the way I enter the info into the HP 12C: 1000 FV 100 PMT 10 n -800 PV i Am I doing something wrong?.. Please HELP!
Found your problem in my user guide. Press ‘STO’ then ‘EEX’ Your calc will work fine after that.
Hit G [End]. You’re calculating as though payments are made at the beginning of the period. Make sure you understand this and G [Beg] before the exam – it can really foul you up.
Anish - Thank you! I finally got rid of that “c” 
Robert - thanks for the tip on function G - beginning & end, I had the BEG on. Where can I find more info about how to properly use this calculator? The youtube instructional videos posted on this forum are not very useful and the PDF guide from the HP12C official website is somehow limited.
Manual (12C): http://h10032.www1.hp.com/ctg/Manual/c00363319.pdf Manual (12C Platinum): http://h10032.www1.hp.com/ctg/Manual/bpia5184.pdf Solutions guidebook: http://h10032.www1.hp.com/ctg/Manual/c00367123.pdf