MULTIPYING TWO DIGIT NUMBERS-34a
       FIRST SIMPIFY THE PROBLEM
   27             20         7
  X 3           X  3   and x 3 
  ---            ---        ---
   81             60        21    then add  60 + 21  = 81

 or    FIRST SIMPIFY THE PROBLEM         or      
   27             27            27                27
 x 23              3            20              X 23
   ---           ---           ---               ---
  621             21           140                81
                  60           400               540
                 ---           ---               ----
                  81     +     540  = 621        621
ESTIMATING THE ANSWER:
1. ROUND EACH NUMBER TO NEAREST EASY NUMBER EXAMPLE:27 =30
                                                    23 =20
                      THEN MAKE AN ESTIMATE BY MULTIPLYING:
                                  20  x 30  = 600
                      So you say the answer should be around 600.