题目内容
1125-997= | 998+1246+9989= | (8700+870+87)÷87= | 125×8.8= |
1.3+4.25+3.7+3.75= | 17.15-(3.5-2.85)= | 3.4×99+3.4= | 4.8×1.01= |
0.4×(2.5÷73)= | (1.6+1.6+1.6+1.6)×25 | (+-)÷= | = |
12.3-2.45-5.7-4.55= | ÷2+×= | 0.125×0.25×64= | 64.2×87+0.642×1300= |
78×36+7.8×741-7= | ×17+×8= | ×+0.125×+0.5= | 2.42÷+4.58×-4÷3= |
25÷100= | 4.25-3-(2-1)= | 3.8÷3.9+3.9÷0.1+0.1÷3.9= | 12.1-(+)×105= |
解:(1)1125-997,
=1125-1000+3,
=125+3,
=128;
(2)998+1246+9989,
=998+(1233+2+11)+9989,
=(998+2)+1233+(11+9989),
=1000+1233+10000,
=12233;
(3)(8700+870+87)÷87,
=8700÷87+870÷87+87÷87,
=100+10+1,
=111;
(4)125×8.8,
=125×8+125×0.8,
=1000+100,
=1100;
(5)1.3+4.25+3.7+3.75,
=(1.3+3.7)+(4.25+3.75),
=5+8,
=13;
(6)17.15-(3.5-2.85)
=17.15+2.85-3.5,
=20-3.5,
=16.5;
(7)3.4×99+3.4,
=3.4×(99+1),
=3.4×100,
=340;
(8)4.8×1.01,
=4.8×1+4.8×0.01,
=4.8+0.048,
=4.848;
(9)0.4×(2.5÷73),
=0.4×2.5÷73,
=1÷73,
=;
(10)(1.6+1.6+1.6+1.6)×25,
=1.6×(4×25 ),
=1.6×100,
=160;
(11)(+-)÷,
=×36+×36-×36,
=16+30-14,
=32;
(12),
=×100+×,
=28+,
=;
(13)12.3-2.45-5.7-4.55,
=(12.3-5.7)-(2.45+4.55),
=6.6-7,
=-0.4;
(14)÷2+×,
=×+×,
=(+)×,
=1×,
=;
(15)0.125×0.25×64,
=(0.125×8)×(0.25×8),
=1×2,
=2;
(16)64.2×87+0.642×1300,
=64.2×(87+13),
=64.2×100,
=6420;
(17)78×36+7.8×741-7,
=7.8×(360+741-1),
=7.8×1100,
=8580;
(18)×17+×8,
=×17+×17,
=(+)×17,
=×17,
=×17,
=;
(19)×+0.125×+0.5,
=(0.875+0.125+1)×0.5,
=(1+1)×0.5,
=2×0.5,
=1;
(20)2.42÷+4.58×-4÷3,
=(2.42+4.58-1)×,
=6×,
=8;
(21)25÷100,
=25÷,
=25×,
=;
(22)4.25-3-(2-1),
=(4.25+1.75)-(+),
=6-6,
=0;
(23)3.8÷3.9+3.9÷0.1+0.1÷3.9,
=(3.8+0.1)÷3.9+3.9÷0.1,
=3.9÷3.9+39,
=1+39,
=40;
(24)12.1-(+)×105,
=12.1-(×105+×105),
=12.1-(7+5),
=12.1-12,
=0.1.
分析:根据小数、分数、整数四则混合运算的顺序进行计算解答.
点评:本题主要考查小数、分数、整数四则混合运算,注意运用运算定律进行简算.
=1125-1000+3,
=125+3,
=128;
(2)998+1246+9989,
=998+(1233+2+11)+9989,
=(998+2)+1233+(11+9989),
=1000+1233+10000,
=12233;
(3)(8700+870+87)÷87,
=8700÷87+870÷87+87÷87,
=100+10+1,
=111;
(4)125×8.8,
=125×8+125×0.8,
=1000+100,
=1100;
(5)1.3+4.25+3.7+3.75,
=(1.3+3.7)+(4.25+3.75),
=5+8,
=13;
(6)17.15-(3.5-2.85)
=17.15+2.85-3.5,
=20-3.5,
=16.5;
(7)3.4×99+3.4,
=3.4×(99+1),
=3.4×100,
=340;
(8)4.8×1.01,
=4.8×1+4.8×0.01,
=4.8+0.048,
=4.848;
(9)0.4×(2.5÷73),
=0.4×2.5÷73,
=1÷73,
=;
(10)(1.6+1.6+1.6+1.6)×25,
=1.6×(4×25 ),
=1.6×100,
=160;
(11)(+-)÷,
=×36+×36-×36,
=16+30-14,
=32;
(12),
=×100+×,
=28+,
=;
(13)12.3-2.45-5.7-4.55,
=(12.3-5.7)-(2.45+4.55),
=6.6-7,
=-0.4;
(14)÷2+×,
=×+×,
=(+)×,
=1×,
=;
(15)0.125×0.25×64,
=(0.125×8)×(0.25×8),
=1×2,
=2;
(16)64.2×87+0.642×1300,
=64.2×(87+13),
=64.2×100,
=6420;
(17)78×36+7.8×741-7,
=7.8×(360+741-1),
=7.8×1100,
=8580;
(18)×17+×8,
=×17+×17,
=(+)×17,
=×17,
=×17,
=;
(19)×+0.125×+0.5,
=(0.875+0.125+1)×0.5,
=(1+1)×0.5,
=2×0.5,
=1;
(20)2.42÷+4.58×-4÷3,
=(2.42+4.58-1)×,
=6×,
=8;
(21)25÷100,
=25÷,
=25×,
=;
(22)4.25-3-(2-1),
=(4.25+1.75)-(+),
=6-6,
=0;
(23)3.8÷3.9+3.9÷0.1+0.1÷3.9,
=(3.8+0.1)÷3.9+3.9÷0.1,
=3.9÷3.9+39,
=1+39,
=40;
(24)12.1-(+)×105,
=12.1-(×105+×105),
=12.1-(7+5),
=12.1-12,
=0.1.
分析:根据小数、分数、整数四则混合运算的顺序进行计算解答.
点评:本题主要考查小数、分数、整数四则混合运算,注意运用运算定律进行简算.
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