In four hours, the party started quieting down. (note the use of the comma) His last song was quite a success. (that's okay) Mathematicians are good at reckoning. (that's okay) I quarreled with all of my neighbors. (I used 'of') The traveler spent the night at the small hotel and then continued on his way. (correction in the spelling of 'traveler' and inclusion of 'on')

A mathematician might argue with the meaning of your sentence! They would probably say that accountants are good at reckoning, and mathematicians are good at reasoning. ;)