btcapital

You should format your calculator to 9 decimal places. on the BA2+ hit the format button by pressing 2nd and hitting the decimal point button. enter 9 under DEC and hit enter.

Further to that if you understand the basic calculation to find EAR you should really be using the ICONV button (press 2nd, then hit the number 2 button). For the question above:

NOM = 6
C/Y = 26
EFF = CPT and you get 6.176315022

Saves time which will help come exam day.