四年級(jí)數(shù)學(xué)下冊(cè)第六單元小數(shù)簡便運(yùn)算

四年級(jí)數(shù)學(xué)下冊(cè)第六單元小數(shù)簡便計(jì)算專項(xiàng)練習(xí)

一、脫式計(jì)算

1.計(jì)算下面各題(能簡算的要簡算)。

6.78+2.04+7.22+5.96

0.25×4.4

2.8×101-2.8

=(6.78+7.22)+(2.04+5.96)

=0.25×4+0.25×0.4

=2.8×(101-1)

=14+8

=1+0.1

=2.8×100

=22

=1.1=280

2.計(jì)算下面各題，怎樣簡便就怎樣計(jì)算。

1.29-3.7+9.71-6.3

300-2730÷91-70400-(1300÷65+35)

=1.29+9.71-(3.7+6.3)

=300-30-70

=400-(20+35)

=11-10

=300-(30+70)

=400-55

=1

=200

=345

125×48

6.45-(2.31-1.55)

64×39+37×39-39

=125×8×6

=6.45-2.31+1.55

=39×(64+37-1)

=1000×6

=6.45+1.55-2.31

=39×100

=6000

=8-2.31

=3900

3.怎樣簡便就怎樣計(jì)算。

103×87-93×87

3000÷125÷8

=(103-93)×87

=3000÷(125×8)

=10×87

=3000÷1000

=870

=3

6.74+12.62+24.38+3.26

23.4-8.54-1.46

=(6.74+3.26)+(12.62+24.38)

=23.4-(8.54+1.46)

=10+37

=23.4-10

=47

=13.4

6.92-(3.2+1.92)

101×78-78

=6.92-1.92-3.2

=(101-1)

×78

=5-3.2

=100×78

=1.8

=7800

4.怎樣算簡便怎樣。

(1)5.02-3.5+0.98

(2)2.88+2.3+4.7

(3)7300÷(73×25)

=(5.02+0.98)-3.5

=2.88+(2.3+4.7)

=7300÷73÷25

=6-3.5

=2.88+7

=100÷25

=2.5

=9.88

=4

(4)1050÷15÷7

(5)80-12.4-7.6

(6)568-(68+178)

=1050÷(15×7)

=80-(12.4+7.6)

=568-68-178

=1050÷105

=80-20

=500-178

=10

=60

=322

5.簡便運(yùn)算。

3.27+5.49-1.27+4.51

9.75-(6.75+0.4)

=3.27-1.27+(5.49+4.51)

=9.75-6.75-0.4

=2+10

=3-0.4

10.27-0.34+1.73-2.66

12.457-(2.457-4.5-5.5)

=10.27+1.73-(0.34+2.66)

=12.457-2.457+(4.5+5.5)

=12-3

=10+10

=9

=20

6.怎樣算簡便就怎樣算:9.25×9.9+92.5%=92.5

7.用簡便方法計(jì)算。

①25×1.25×32

②(3.75-2.9+2.25)÷31%

=25×1.25×4×8

=(3.75+2.25-2.9)÷31%

=(25×4)×(1.25×8)

=(6-2.9)÷0.31

=100×10

=3.1÷0.31

8.用你喜歡的方法計(jì)算

5/8+3/4×60%12.5×25%×20+3.2=5/8+3/4×3/5=12.5×?×20+3.2

=5/8+9/20=62.5+3.2=4340=65.7

0.875×25+75×87.5%+87.5

6.7-3.25+13.3-0.75

=0.875×25+75×0.875+0.875×100

=(6.7+13.3)-(3.25+0.75)

=0.875×(25+75+100)

=20-4

=0.875×100×2=16=1759.計(jì)算下面各題。你認(rèn)為怎樣簡便就怎樣算。

1.2÷2.5(30.5-8.22)×0.4

34.7÷12.5÷0.8

=(1.2×4)÷(2.5×4)

=22.28×0.4

=34.7÷(12.5×0.8)

=4.8÷10

=8.912=34.7÷10

=0.48

=3.47

10.能簡算的要簡算。

125%-68%+0.7

(45%+25%)×4

34%+79%+21%+66%

=1.25-0.68+0.7

=(0.45+0.25)×4

=0.34+0.79+0.21+0.66

=0.57+0.7

=0.7×4

=(0.34+0.66)+(0.79+0.21)

=1.27

=2.8

=1+1=2

120%+89%+11%

2-45%-55%

36%×1.7+1.7×64%

=1.2+0.89+0.11

=2-0.45-0.55

=0.36×1.7+1.7×0.64

=1.2+(0.89+0.11)

=2-(0.45+0.55)

=(0.36+0.64)×1.7

=1.2+1=2-1

=1×1.7

11.計(jì)算下面各題，怎樣簡便怎樣計(jì)算，要寫出必要的計(jì)算過程。

①10-2.8-7.2

②16.8÷0.5÷2

③3.7×0.25×4

=10-(2.8+7.2)=16.8÷(0.5×2)

=3.7×(0.25×4)

=10-10

=16.8÷1

=3.7×1

=0

=16.8

=3.7

12.怎樣算簡便就怎樣算。

25.86+7.8-5.86

0.8×3.37×12.5

3.2+6.8×1.25×8

=25.86-5.86+7.8

=(0.8×12.5)×3.37

=3.2+6.8×(1.25×8)

=20+7.8

=10×3.37

=3.2+6.8×10

=27.8

=33.7

=3.2+68

918-(107+218)

45×98

25×(20+4)

=918-107-218

=45×(100-2)

=25×20+25×4

=918-218-107

=45×100-45×2

=500+100

=700-107

=4500-90