下面各题,怎样算简便就怎样算.1080+270÷18﹣864 7.54++2.46+ (2.4﹣)÷0.625+2.5×12.5×40×0.8 6﹣÷﹣ .
36×72+36×27+36 125×32×25 4.64﹣(0.64+3.62)21÷9+22÷9+23÷9+24÷9 199999.9+19999.8+1999.9+199.8+19.9+0.7.
321×3.3﹣123÷= 326 .
(7.5+7.5+7.5+7.5)×125×4.
1999+999×999.
8888008×125.