code: private void scanNumber() {
  
          if (mInput >= '0' && mInput <= '9') {
              mOutput.append(mInput);
              mPos++;
          } else {
              // could be an e-number
              if (mInput == 'E' || mInput == 'e') {
                  mStartState = State.E_NUM;
              }
              mFinnished = true;
          }
      }
docs: Scans a number token. A number only consists of digits.