下面各题,能简算的要用简便方法计算.2.9+0.46+7....

①2.9+0.46+7.1+0.54=(2.9+7.1)+(0.46+0.54)=10+1=11;②(31.6-11.7)÷2.5÷0.4=19.9÷(2.5*0.4)=19.9÷1=19.9;③0.4*37*25=37*(0.4*25)=37*10=370;④4.97÷1.25+3.03*8=4.97÷10 8 +3.03*8=0.497*8+3.03*8=(0.497+3.03)*8=3.527*8=28.216.

(1)2.9+6.46+7.1+3.54,=(2.9+7.1)+(6.46+3.54),=10+10,=20;(2)2.3÷8÷12.5,=2.3÷(8*12.5),=2.3÷100,=0.023;(3)0.4*(25+2.5),=0.4*25+0.4*2.5,=10+1,=11;(4)4.95*[2.46÷(5.58-5.28)],=4.95*[2.46÷0.3],=4.95*8.2,=40.59;(5)9.16-1.25-3.16-2.75,=9.16-3.16-1.25-2.75,=(9.16-3.16)-(1.25+2.75),=6-4,=2.

解;①7.9+0.46-0.9+0.54,=(7.9-0.9)+(0.46+0.54),=7+1,=8;②30÷2.5+1.6*2.5,=12+4,=16;③1.25*19.4*0.8,=(1.25*0.8)*19.4,=1*19.4,=19.4;④4.3*10.2,=4.3*(10+0.2),=4.3*10+4.3*0.2,=43+0.86,=43.86.

①2.9+0.46+7.1+0.54 =(2.9+7.1)+(0.46+0.54)=10+1=11;②582÷0.8÷12.5=582÷(0.8*12.5)=582÷10=58.2;③(31.6-11.7)÷2.5÷0.4=19.9÷(2.5*0.4)=19.9÷1=19.9.

(1)2.5*道(2.9+2.9+2.9+2.9),=2.5*版4*2.9,权=10*2.9,=29;(2)(2 3 -5 9 *3 8 )÷7 16 ,=(2 3 -5 24 )÷7 16 ,=11 24 ÷7 16 ,=11 21 ;(3)(1 6 +1 9 -1 12 )*36,=1 6 *36+1 9 *36-1 12 *36,=6+4-3,=10-3,=7;(4)4÷4 9 -4 9 ÷16,=9-1 36 ,=835 36 .

(1)6.01-2.9+7.99,=6.01+7.99-2.9,=14-2.9,=11.1;(2)29.44-(9.44+0.825),=29.44-9.44-0.825,=20-0.825,=19.175;(3)15.36-(6.3-4.64),=15.36+4.64-6.3,=20-6.3,=13.7;(4)5.9+0.2-5.9-1-0.2,=(5.9-5.6)+(0.2-0.2)-1,=0+0-1,=-1.

(1)4.02-3.5+0.98,=5-3.5,=1.5;(2)7.08-0.74-1.26,=7.08-2,=5.08;(3)7.75*[20÷(3.24-3.04)],=7.75*【20÷0.2】,=7.75*100,=775;(4)4.05÷0.81+2.4,=5+2.4,=7.4;(5)3.7*4.5-4.4*3.7,=3.7*0.1,=0.37;(6)0.034*0.5*0.6,=0.034*0.3,=0.0102.

17*40=680, 100-63=37, 3.2+1.68=4.88, 2.8*0.4= 1.12 14-7.4=6.6, 1.92÷0.04=48, 0.32*500=160, 0.65+4.35= 5 10-5.4=4.6, 4÷20=0.2, 3.5*200=700, 1.5-0.06=1.44 0.75÷15=0.05, 0.4*0.8=0.32, 4*0.25=1, 0.36+1.54=2 1.01*99=99.99, 420÷35=12,

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