> Watson cannot do simple arithmetic

Can you provide some sources? I assumed that if Watson could win at Jeopardy, it would be able to do simple math problems.

Edit: I am not sure what you mean about Watson's inability to do arithmetic.

"The two major goals for IBM and RPI are to improve Watson's mathematical ability and to aid its recognition and interpretation of new words."

http://www.gizmag.com/ibm-watson-supercomputer-rpi/26038/

All accounts seem to allude to Watson's ability to infer natural language and problem solve, including arithmetic. I have not found anything explicitly saying it can not perform simple arithmetic.