nathancamp:
Looking back,I think you want Serial.write(digit);
CrossRoads:
Perhaps this?
Serial.println(char(digit));
It depends on the OP's goal. If it's to print the representations of each ASCII code, then yes those will do it. If it's to print an ascending sequence of numbers then those won't work(except for values of digit between 48 and 57).
Do you use a keyboard where the numeric keypad is integrated in the normal keys? Usually found on small laptops like e.g. File:Acer Aspire One 532h.jpg - Wikimedia Commons? If so, sounds like you have to 'push' an additional key to switch between numeric and alpha. But tat would be normal behaviour for those keyboards.
For the one linked, 1 -> J, 2 -> K, etc. Your keyboard might be different.