望采纳谢谢。(1)2.5*32*0.125 =(2.5*4)*(8*0.125) =10*1 =10 (2)3.5-7+6.5 =3.5+6.5-7 =3 (3)1.2×2.5+0.8×2.5 =2.5(1.2+0.8) =25 (4)8.9×1.25-0.9×1.25 =1.25(8.9-0.9) =10 (5)12.5×7.4×0.8 =12.5×0.8×7.4 =74 (6)6.5×9.5+6.5×0.5 =6.5×(9.5+0.5) =6.5×10 =65 (7)0.35×1.6+0.35×3.4 =0.35*(1.6+3.4) =0.35*5 =1.75 (8)6.72-3.28-1.72 =6.75-(3.28+1.72) =6.75-5 =1.75 (9)0.45+6.37+4.55 =0.45+4.55+6.37 =5+6.37 =11.37 (10)28×12.5-12.5×20 =(28-20)*12.5 =8*12.5 =100 (11)23.65-(3.07+3.65) =23.65-3.65-3.07 =20-3.07 =16.93 (12)(4+0.4×0.25)8×7×1.25 =(4+1)*7*10 =5*7*10 =350 (13)1.65×99+1.65 =1.65*(99+1) =1.65*100 =165 (14)27.85-(7.85+3.4) =27.85-7.85+3.4 =20+3.4 =23.4 (15)48×1.25+50×1.25×0.2×8 7.8×9.9+0.78 =7.8*(9.9+0.1) =7.8*10 =78 (16)4.8×46+4.8×54 =(46+54)*4.8 =100*4.8 =480 (17)673-327-173 =673-(327+173) =673-500 =173 (18)4.44*2.5 =1.11*(4*2.5) =1.11*10 =11.1 (19)3.5÷1.4 =(3.5÷0.7)÷(1.4÷0.7) =5÷2 =2.5 (20)1+2+3+4+5......+99+100 =(1+99)+(2+98)+(3+97)+......+(49+51)+50 =(100÷2-1)*100+50 =4900+50 =4950⑴运用加法交换律进行简便计算。 0.88+5.6+0.12 1.78+3.5+0.22 5.6+2.08+14.4 =0.88+0.12+5.6 =1.78+0.22+3.5 =5.6+14.4+2.08 =1+5.6 =2+3.5 =20+2.08 =6.6 =5.5 =22.08 ⑵运用加法结合律进行简便计算 2.3+(0.56+4.7) 28.6+0.54+0.46+1.4 5.82+4.56+5.44 =(2.3+4.7)+0.56 =(28.6+1.4)+(0.54+0.46) =5.82+(4.56+5.44) =7+0.56 =30+1 =5.82+10 =7.56 =31 =15.82 ⑶、运用乘法交换律进行简便计算。 25×0.37×0.4 7.5×0.39×4 6.5×1.1×4 1.25×3.9×0.8 =25×0.4×0.37 =7.5×4×0.39 =6.5×4×1.1 =1.25×0.8×3.9 =10×0.37 =30×0.39 =26×1.1 =1×3.9 =3.7 =11.7 =28.6 =3.9 ⑷、运用乘法结合律进行简便计算。 1.9×7.5×8 6.2×0.8×2.5 4.3×1.5×6 4.1×3.5×2 =1.9×(7.5×8) =6.2×(0.8×2.5) =4.3×(1.5×6) =4.1×(3.5×2) =1.9×60 =6.2×2 =4.3×9 =4.1×7 =114 =12.4 =38.7 =28.7 ⑸、运用乘法分配律的加法进行简算。 13.6×4.6+4.6×6.4 0.72×23+77×0.72 2.6×32+32×2.4 =(13.6+6.4)×4.6 =(23+77)×0.72 =(2.6+2.4) ×32 =20×6.4 =100×0.72 =5×32 =128 =72 =160 ⑹、运用乘法分配律的减法进行简算。 12×5.9-5.9×2 4.6×2.5-2.5×0.6 101×9.7-9.7 =(12-2) ×5.9 =(4.6-0.6)×2.5 =(101-1)×9.7 =(12-2) ×5.9 =(4.6-0.6)×2.5 =(101-1)×9.7 =10×5.9 =4×2.5 =100×9.7 =59 =10 =970 ⑺、运用减法的运算规律进行简便计算。 1.8-0.45-0.55 54.4-4.6-5.4 35.6-0.13-0.47 =1.8-(0.45+0.55) =54.4-(4.6+5.4) =35.6-(0.13+0.47) =1.8-1 =54.4-10 =35.6-0.6 =0.8 =44.4 =35 ⑻、运用除法的运算规律进行简便计算。 4.5÷4÷7.5 14.8÷1.25÷8 18.5÷4÷1.25 5.4÷4÷0.45 =4.5÷(4×7.5) =14.8÷(1.25×8) =18.5÷(4×1.25) =5.4÷(4×0.45) =4.5÷30 =14.8÷10 =18.5÷5 =5.4÷0.18 =0.15 =1.48 =3.7 =30 ⑼综合运用各种运算定律进行简算。 2.54+2.46+0.44+0.54 10.7×0.4-6.7×0.4 0.5×3.2×1.25 =(2.54+2.46)+(0.44+0.54) =(10.7-6.7)×0.4 =(0.5×4)×(0.8×1.25) =5+1 =4×0.4 =2×1 =6 =1.6 =2 89.7+5.8-9.7+4.2 99×0.38+0.38 360÷(18×0.4) =(89.7-9.7)+(5.8+4.2) =(99+1) ×0.38 =360÷18÷0.4 =80+10 =100×0.38 =20÷0. 4 =90 =38 =50 4.8×12.5 2.5×1.6×12.5 3.2×102 =0.6×(8×12.5) =(2.5×0.2)×(8×12.5) =3.2×(100+2) =0.6×100 =0.5×100 =3.2×100+3.2×2 =60 =50 =320+6.4 =326.4