199.9×19.98-19.98×1.987 简算

199.9×19.98-19.98×1.987 简算 199.9*19.98-199.8*19.97 199.9×19.98-19.99×199.8用简便方法怎么计算 199.9×19.98-199.8×19.97(简便计算,递等式)给好评. 2.4*5.8+0.28*4.2简便算法199.7*19.98-199.9*19.96 199.9*19.98-199.8*19.97用简便方法计算（要过程）. 第一讲全部答案,2000×199.9-1999×199.8 19.98×37-199.8×1.9+1.998×820 9.56×4.18-7.3×4.18-0.26×4.18 计算 199.8+19.98+1.998+2.222 奥数题19.9+19.98+19.997+19.9996 99.9^2+19.98+1/100 19.9+19.98+19.997+19.996 巧算 199.8+19.98+1.998+2.222的简便方法? 简算：19.99乘19.98-19.97乘19.96 简便计算;19.99*19.98-19.97*19.96 19.98×51+199.8×3.9+199.8是多少 1998+199.8+19.98+1.998+2.222= 199.8+19.98+1.998+2.222 要过程 19.98×37-199.8×1.9 1998×0.