| a) | Remplace les pointillés par le naturel qui convient. | 
| 64 
        . 62  | = 
        64 + 2 = 66 | (4 
        . 3)3 
         | = 
        43 . 33 | (53)5 
         | = 515 
           
 | 
| 34 
        . 35 
         |  = 
          39 | 22 
        . 24  | = 22 
          + 4 
 | (3 
        . 8)2  | = 
        32 . 
        82 | 
| (43)2 
         | = 43 
          . 2 | 74 
        . 71 | = 
        75 = 74 + 1 | 53 
        . 43 | = 
        (5 . 4)3 |