第一棵树上原来有{#blank#}1{#/blank#}只鸟.第二棵树上原来有{#blank#}2{#/blank#}只鸟.第三棵树上原来有{#blank#}3{#/blank#}只鸟．

4 × 1 =        3 × 2 =         6 × 2 =        1 × 8 =

4 + 1 =          3 + 2 =           6 + 2 =          1 + 8 =

9－2＝                      6＋4＝                    9＋1＝                      1＋1＝                      9－9＝

5＋5＝                    10－1＝                    2＋6＝                      9－7＝                      10－3＝

8－4＝                      6－3＝                      8＋1＝                      5－1＝                      8＋2＝

6＋3＝                      7＋3＝                    10－5＝                    0＋0＝                      3－2＝