(1)7+9×9=88,
6+98×9=888,
5+987×9=8888,
4+9876×9=88888,
再写出几个:
3+98765×9=888888,
2+987654×9=8888888,
1+9876543×9=88888888;
(2)1×9+(1+9)=19,
12×9+(12+9)=129,
123×9+(123+9)=1239,
1234×9+(1234+9)=12349;
在写出几个:
12345×9+(12345+9)=123459;
123456×9+(123456+9)=1234569;
1234567×9+(1234567+9)=12345679;
12345678×9+(12345678+9)=123456789.