(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. |