分析:
(1)先根據(jù)四則混合運算的順序確定應(yīng)該先算什么后算什么:只有一級運算時,從左到右計算;有兩級運算時,先算乘除,后算加減.有一層括號時,先算括號里的;有多層括號時,先算小括號里的. (2)能夠運用簡便算法的題目,根據(jù)所學(xué)定律選擇適合的簡便方法. |
解答:解:
(1)6.5×8+3.5×8-44,
=(6.5+3.5)×8-44,
=10×8-44,
=80-44,
=36;
(2)8.5+(5.6-4.8)×13,
=8.5+0.8×13, =8.5+10.4, =18.9;
(3)1.9-1.9×(1.9-1.9), =1.9-1.9×0, =1.9-0, =1.9;
(4)×29+×29+29 =(++1)×29, =2×29, =58;
(5)1×÷×, =×2000×, =20×, =2;
(6)×101-, =(101-1)×, =100×, =28;
(7)49.5×10-(50-)×0.6, =49.5×10.6-49.5×0.6, =49.5×(10.6-0.6), =49.5×10, =495;
(8)×4+5÷1+, =×4+5×+, =(4+5+1)×, =11×, =7;
(9)÷[×(1-)], =÷[×], =÷, =×, =;
(10)897×-37.5%+104×0.375, =897×0.375-0.375+104×0.375, =(897-1+104)×0.375, =1000×0.375, =375;
(11)[+×(-0.375)]÷, =[+×(-)]÷, =[+×]÷, =[+]÷, =×, =;
(12)+9+99+999+9999, =(9+99+999+9999)+×5, =9+99+999+9999+4, =(9+1)+(99+1)+(999+1)+(9999+1), =10+100+1000+10000, =11110;
(13)4-(2+), =4-2-, =2-, =. |
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點評:此題主要考察四則混合運算的順序和簡便算法的靈活運用,要根據(jù)每一題的特點選擇適合的方法.