口算下面各题 (1)2.5+3.2= (2)9.8-4.8= (3)1.29-0.18= (4)2.26+0.9= (5)8-0.82= (6)0.75+0.25= (7)1.4+0.5= (8)10.8-8.5= (9)6.4+1.07= (10)0.55+5.5= (11)1.05-0.09= (12)0.6+6.45=
计算下面各题. (1)2.89×6.37+0.137×28.9+289×0.0226; (2)1+2+3+4+5+6; (3); (4)(5﹣1.8)÷[(1.15+)×1]; (5)+++…+(答案写成最简形式即可)
巧算.+++++++ (1++)×(+++)﹣(1++++)×(+)
(新邵县)化简下面各比,并求出比值 20:8 25%:0.75.
(成都)能用简便方法的要用简便方法 (1+2+3+4+…+999+1000)﹣(2+4+6+8+…+996+998)
(长沙)巧算. ①++++++ ②(++)×(+++1)+1﹣(++)2﹣(++)