考點:整數(shù)四則混合運算,運算定律與簡便運算,小數(shù)四則混合運算
專題:運算順序及法則,運算定律及簡算
分析:(1)先算小括號里面的除法,再算小括號里面的減法,最后算括號外的加法;
(2)先算除法,再算乘法,最后算減法;
(3)按照從左到右的順序計算;
(4)先算小括號里面的乘法,再算小括號里面的減法,然后算括號外的除法,最后算括號外的乘法;
(5)按照從左到右的順序計算;
(6)根據(jù)加法交換律、結(jié)合律和減法的性質(zhì)簡算;
(7)根據(jù)減法的性質(zhì)簡算;
(8)先算小括號里面的減法,再算中括號里面的除法,然后算中括號里面的減法,最后算括號外的乘法;
(9)先算小括號里面的減法,再根據(jù)乘法分配律簡算;
(10)先根據(jù)積不變規(guī)律變形,再根據(jù)乘法分配律簡算.
解答:
解:(1)45+(1849-2958÷29)
=45+(1849-102)
=45+1747
=1792;
(2)180-180÷12×5
=180-15×5
=180-75
=105;
(3)9600×45÷24
=432000÷24
=18000;
(4)(20-1.25×5)÷2.5×4
=(20-6.25)÷2.5×4
=13.75÷2.5×4
=5.5×4
=22;
(5)29.76-3.8+6.2
=25.96+6.2
=32.16;
(6)4.6-0.97+15.4-7.03
=(4.6+15.4)-(0.97+7.03)
=20-8
=12;
(7)4.83-(3.83-1.87)
=4.83-3.83+1.87
=1+1.87
=2.87;
(8)2.5×[723.6÷15-(41.47-38.23)]
=2.5×[723.6÷15-3.24]
=2.5×(48.24-3.24)
=2.5×45
=112.5;
(9)732×54+732×(100-54)
=732×54+732×46
=732×(54+46)
=732×100
=73200;
(10)99999×77778+33333×66666
=99999×77778+99999×22222
=99999×(77778+22222)
=99999×100000
=9999900000.
點評:此題是考查四則混合運算,要仔細(xì)觀察算式的特點,靈活運用一些定律進(jìn)行簡便計算.