The answers to your questions are as follows:
   
         1) 6.27 + 24.5 = 31.22
         2) 81kg
         3) 654729O75
         4) 2268Og or 22.68kg
         5) 3.141592654
         6) 31O.OO
         7) a) 45O    b) 65.26  c) 3.1415
         8) 67.6O
         9) 159O.82359
        1O) 7.787
        
   Score : 1O/1O - Well done
           between 7 and 1O - Ok but more practice is needed.
           between 5 and  7 - Errors like this cost you a grade in the exam.
           less than 5      - Poor result - Try them again!
           
   There are more questions to answer, why not try them if you have time.