①88.2÷9=9.8          ②88.83÷9=9.87       ③88.884÷9=9.876

④88.8885÷9=         ⑤88.88886÷9=       ⑥88.888887÷9=

＋ ＋ ＝（1－ ）＋（ － ）＋（ - ）

＋ + + + ＝

99×0.77=76.23

999×0.777=776.223

9999×0.7777=7776.2223

那么：999999×0.777777=

6.6×6.9=45.54

6.66×66.9=445.554

6.666×666.9=

6.6666×6666.9=

6.66666×66666.9=

6.6×6.7=44.22

66.6×66.7=4442.22

666.6×666.7=444422.22

66.666×66.667=

666.666×666.667=

6.666666×6666.667=

1×3+1＝2²

2×4+1＝3²

3×5+1＝4²

……

×+1＝2022²

n×（n+2）+1＝²（n为自然数）