+      =  10
                              9  +      =  10
                                  =    
                                      
                                 =
                                      
                               2
                                  =      
                               2
                                  =  9
                                  =    
                                  +      =  18
                                  +  3  =  18
                                  =      
                                  +      +      +      =  15  +  9  +  3  +  1  =  28
                              Jawaban: A
                          3. Potongan tali tersebut mengikuti barisan geometri
                              Paling pendek :   = 4     
                                                1
                              Paling Panjang    = 512     
                                                8
                              Panjang tali semula    +    +    + ⋯ … . . +  
                                                                3
                                                                               8
                                                    1
                                                          2
                                 = 512
                               8
                                  7
                                .    = 512
                                  7
                              4.    = 512
                               7
                                 = 512/4
                               7
                                 = 128
                               7
                                 = 27
                                 = 2
                                                              28