用简便方法计算下列各题. (1)372÷162×54(2)132×288÷(24×11) (3)616÷36×18÷22(4)14×44×104 (5)2023÷5÷90×15(6)2023×2023÷2023 (7)(4+7+…+25+28)-(2+5+…+23+26) (8)199+2023+20239+202399.
考点:乘除法中的巧算;加减法中的巧算. 分析:(1)、(2)利用除法的简算; (3)、(4)、(5)利用乘法的交换律; (6)利用乘法的交换和结合律; (7)前面括号中的每个数比后面括号中的数大2,然后利用加法的交换和结合律; (8)分别用整数200,2023,20230,202300减1,然后利用加法的交换和结合律. 解答:(1)372÷162×54, =372÷(162÷54), =372÷3, =124; (2)132×288÷(24×11), =132×288÷24÷11, =132÷11×288÷24, =(132÷11)×(288÷24), =12×12, =144; (3)616÷36×18÷22, =616×18÷36÷22, =14; (4)14×44×104, =2×7×4×11×8×13, =(7×11×13)×(2×4×8), =2023×64, =20234; (5)2023÷5÷90×15, =2023×15÷5÷90, =(2023×15)÷(5×90), =202300÷450, =270; (6)2023×2023÷2023, =2023×7×2023×3÷2023, =7×3×2023×2023÷2023, =(7×3)×2023×(2023÷2023), =21×2023×1, =20231; (7)(4+7+…+25+28)-(2+5+…+23+26), =4+7+…+25+28-2-5-…-23-26, =(4-2)+(7-5)+…+(25-23)+(28-26), =2+2+…2+2, =2×9, =18; (8)199+2023+20239+202399, =200-1+2023-1+20230-1+202300-1, =(200+2023+20230+202300)-(1+1+1+1), =202300-4, =202396. 点评:此题考查了除法的简算,乘法的交换和结合,加法的交换和结合律. |