计 算 (1)8+3+7= (2)12-9-3= (3)3+7+1= (4)9+2+4= (5)6+5+3= (6)6+4+8= (7)3+6+9= (8)6+4+2= (9)11-1-8= (10)2+8+2= (11)4+4+3= (12)7+2+3= (13)11-2-8= (14)11-6-3= (15)14-7-4=
直接写出得数+= ﹣= 99×=÷37=999×222+333×334= (798×567+351)÷(798×568﹣447)=
求未知数x ①4x+7.1="12.5" ②x=0.6;③x:14%=:0.8.
简便计算. (1) (2) (3)562﹣552+542﹣532+…+22﹣12 (4)(2007×2008×2009×2010+1)﹣(20082+2007)2.
每题都要有必要的计算过程. ①23×2424﹣24×2323 ②52.44×79.45+159×47.56+79.55×52.44 ③ ④ ⑤.
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)