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)
巧算.+++++++ (1++)×(+++)﹣(1++++)×(+)
(新邵县)化简下面各比,并求出比值 20:8 25%:0.75.