脫式計算(能用簡便方法的要用簡便方法)5

2021-03-17 01:27:42 字數 8147 閱讀 4072

1樓:楊冪臭腳笆璳

(1)5.5×17.3+2.7×5.5

=5.5×(17.3+2.7)

=5.5×20

=110;

(2)4.6×(1-0.25)+0.75×5.4=4.6×0.75+0.75×5.4

=0.75×(4.6+5.4)

=0.75×10

=7.5;

(3)0.25×1.25×0.16

=0.25×1.25×(0.2×0.8)

=(0.25×0.2)×(1.25×0.8)=0.05×1

=0.05;

(4)12.5×1.7+9.3×12.5-12.5=12.5×(1.7+9.3-1)

=12.5×10

=125.

脫式計算(能簡算的要用簡便方法計算): ①80÷(1-84%) ②5-5× 2 5 +

2樓:臥牛

①80÷(1-84%),

=80÷0.16,

=500;

②5-5×2 5

+3 5

,=5-2+3 5

,=33 5

;③0.25×32×12.5%,

=0.25×4×8×0.125,

=(0.25×4)×(8×0.125),

=1×1,

=1;④7 9

÷11 5

+2 9

×511

,=7 9

×511

+2 9

×511

,=(7 9

+2 9

)×511

,=1×5

11,=511.

3樓:冼棟屈嘉穎

解:①80÷(1-84%),

=80÷0.16,

=500;

②5-5×

25+35,

=5-2+35,

=335;

③0.25×32×12.5%,

=0.25×4×8×0.125,

=(0.25×4)×(8×0.125),

=1×1,

=1;④79÷115+29×511,

=79×511+29×511,

=(79+29)×511,

=1×511,

=511.

脫式計算.(能用簡便方法的用簡便方法).3.78-1.46+1.54 17.5-5.15-1.85 4.1×9.

4樓:湛夜綠

(ⅰ)由sn=n+3

2an,①當n≥2時,sn?1=n?1+32an?1,②

兩式相減得an=1+3

2an?3

2an?1,即an=3an-1-2.當n≥2時,an?1an?1?1

=3an?1?2?1

an?1?1

=3為定值,

由sn=n+3

2an,令n=1,得a1=-2.所以數列是等比數列,公比是3,首項為-3.

所以數列的通項公式為an=1-3n.(4分)(ⅱ)∴b2=-8,b20=-80.由是等差數列,求得bn=-4n.tn=b1

a1?1

+b2a2?1

++bn?1

an?1?1

+bnan?1

=4[1

31+2

32++(n?1)

3n?1

+n3n

],而1

3tn=4[1

32+2

33++(n?1)

3n+n

3n+1

],相減得2

3tn=4(1

31+1

32++1

3n?n

3n+1

),即tn=2(1

30+1

31++1

3n?1

)?2n

3n,則tn=21?(13)n

1?13

?2n3n

=3?2n+3

3n. (8分)

∵tn+1?tn=?2n+5

3n+1

+2n+3

3n=4n+4

3n+1

>0,故遞增∴當n∈n*時,tn的最小值為43(10分)

∵不等式t

脫式計算(能用簡便方法計算的要用簡便方法計算)185-25-75 6495-(495-299) 200×4+300 9999+999+9

5樓:我是神嗷

(1)185-25-75

=185-(25+75)

=185-100

=85;

(2)6495-(495-299)

=6495-495+299

=6000+299

=6299;

(3)200×4+300

=800+300

=1100;

(4)9999+999+99+9

=(10000-1)+(1000-1)+(100-1)+(10-1)=(10000+1000+100+10)-(1+1+1+1)=11110-4

=11106.

脫式計算下面各題(能簡算的要用簡便方法計算,並寫出簡算過程). (84×27-2166)÷17 115×3.

6樓:小柒

①(84×27-2166)÷17,

=(2268-2166)÷17,

=102÷17,

=6;②11

5×3.7+5.3÷5

11+2.2,

=2.2×3.7+5.3×2.2+2.2,=2.2×(3.7+5.3+1),

=2.2×10,

=22;

③(0.75÷3-0.1)×(1-23),=(0.25-0.1)×13,

=0.15×13,

=0.05.

五年級上冊數學簡便計算30道題及答案

7樓:阿維

1、24.6-3.98+5.4-6.02

解析:此題利用加法交換結合律,湊整再計算。步驟如下:

24.6-3.98+5.4-6.02

=(24.6+5.4)-(3.98+6.02)

=30-10

=202、27×17/26

解析:此題先用加法分配律,把27轉換成(26+1),再利用乘法結合律,使得運算簡便。

27×17/26

=(26+1)×17/26

=26×17/26+1×17/26

=17+17/26

=17又17/26

3、528-99

解析:利用湊整法和減法結合律計算,先利用湊整法把99變換為(100-1),再運用a-b-c=a-(b+c)來簡便計算,步驟如下:

528-99

=528-(100-1)

=528-100+1

=428+1

=429

4、1.2×2.5+0.8×2.5

解析:運用提取公因數的方法,公式:ac+ab=a(b+c),提取公因數2.5,1.2和0.8相加正好湊整數,使得運算簡便。

1.2×2.5+0.8×2.5

=(1.2+0.8)×2.5

=2×2.5

=55、2.96×40

解析:此題先利用乘法分配律,把2.96×40轉換成29.6x4,再利用乘法結合律來簡便計算。

2.96×40

=29.6x4

=(30-0.4)x4

=30×4+0.4×4

=120-1.6

=118.4

6、0.36 x 1.5 - 0.45 

解析:此題運用乘法分配律,把0.45轉換成1.5 x 0.3 ,即可提取公因數1.5,再根據乘法結合律進行簡便計算。

0.36 x 1.5 - 0.45

= 0.36 x 1.5 - 1.5 x 0.3

= 1.5 × (0.36 - 0.3)

= 1.5 × 0.06

= 0.09

7、46×44/45

解析:此題先利用加法分配律把46轉換成(45+1),再利用乘法結合律:(a×b)×c=a×(b×c)使得運算簡便。

46×44/45

=(45+1)×44/45

=45×44/45+44/45

=44+44/45

=44又44/45

8、1.6×7.5×1.25

解析:此題利用乘法分配律把1.6,轉化成2×0.8,再利用乘法結合律:(a×b)×c=a×(b×c)湊整,進行簡便計算。

1.6×7.5×1.25

=2×0.8×7.5×1.25

=(2×7.5)×(0.8×1.25)

=15×1

=159、0.72×10.1

解析:此題先利用加法分配律,把10.1轉換成10+0.1,再利用乘法結合律使得運算簡便。

0.72×10.1

=0.72×(10+0.1)

=0.72×10+0.72×0.1

=7.2+0.072

=7.272

8樓:慕容家族創創大

公式1:a-b-c = a-(b+c)

10-0.432 -2.568

9.3-5.26-2.74

13.4-(3.4+5.2)

14.9-(5.2+4.9)

18.32-5.47-4.32

17.29-5.28-6.29

公式2:(axb)xc=ax(bxc)

25×6.8×0.04

0.25×32×0.125

6.4×1.25×12.5

公式3:c×(a+b)=ca+cb

0.45×201

0.58×10.1

50.2×99+50.2

4.7×9.9

3.28x5.7+6.72x5.7

2.1×99+2.1

1.7×9.9+0.17

23×0.1+2.3×9.9

0.18+4.26-0.18+4.26

0.58x1.3÷0.58x1.3

7.3÷4+2.7x0.25

3.75x0.5-2.75÷2

5.26x0.125+2.74÷8

公式4:a÷b÷c=a÷(b×c)

6.3÷1.8

4.2÷3.5

9.5÷(1.9 × 8)

12.8÷(0.4×1.6)

930÷0.6÷5

63.4÷2.5÷0.4

(7.7+1.54)÷0.7

(11.7+9.9)÷0.9

簡便計算:

100-0.99

10.99+9.87

4.089÷0.047

0.24×390

6.9+4.8+3.1

0.456+6.22+3.78

15.89+(6.75-5.89)

4.02+5.4+0.98

5.17-1.8-3.2

13.75-(3.75+6.48)

3.68+7.56-2.68

7.85+2.34-0.85+4.66

35.6-1.8-15.6-7.2

3.82+2.9+0.18+9.1

9.6+4.8-3.6

7.14-0.53-2.47

5.27+2.86-0.66+1.63

13.35-4.68+2.65

73.8-1.64-13.8-5.36

47.8-7.45+8.8

0.398+0.36+3.64

15.75+3.59-0.59+14.2566.86-8.66-1.34

0.25×16.2×4

(1.25-0.125)x8

3.6x102

3.72x3.5+6.28x3.5

36.8-3.9-6.1

4.8×7.8+78×0.52

32+4.9-0.9

4.8×100.1

56.5×9.9+56.5

7.09x10.8-0.8x7.09

25.48-(9.4-0.52)

4.2÷3.5

320÷1.25÷8

18.76×9.9+18.76

3.52÷2.5÷0.4

3.9-4.1+6.1-5.9

5.6÷3.5

9.6÷0.8÷0.4

4.2×99+4.2

17.8÷(1.78×4)

0.49÷1.4

1.25×2.5×32

3.65×10.1

15.2÷0.25÷4

0.89×100.1

146.5-(23+46.5)

3.83×4.56+3.83×5.44

4.36×12.5×8

9.7×99+9.7

27.5×3.7-7.5×3.7

8.54÷2.5÷0.4

0.65×101

3.2×0.25×12.5

7.2×0.2+2.4×1.4

8.9×1.01

7.74×(2.8-1.3)+1.5×2.263.9×2.7+3.9×7.3

18-1.8÷0.125÷0.8

12.7×9.9+1.27

21×(9.3-3.7)-5.6

15.02-6.8-1.02

5.4×11-5.4

2.3×16+2.3×23+2.3

9.43-(6.28-1.57)

3.65×4.7-36.5×0.37

46×57+23×86

13.7×0.25-3.7÷4

2.22×9.9+6.66×6.7

101×0.87-0.91×87

10.7×16.1-15.1×10.7

0.79×199

4.8+8.63+5.2+0.37

5.93+0.19+2.81

1.76+0.195+3.24

2.35+1.713+0.287+7.651.57+0.245+7.43

6.02+3.6+1.98

0.134+2.66+0.866

1.27+3.9+0.73+16.1

7.5+4.9-6.5

3.07-0.38-1.62

1.29+3.7+2.71+6.3

8-2.45-1.55

3.25+1.79-0.59+1.75

23.4-0.8-13.4-7.2

0.32×403

3.2+0.36+4.8+1.64

1.23+3.4-0.23+6.6

0.25×36

12.7-(3.7+0.84)

36.54-1.76-4.54

0.25×0.73×4

7.6×0.8+0.2×7.6

0.85×199

0.25×8.5×4

1.28×8.6+0.72×8.6

12.5×0.96×0.8

10.4-9.6×0.35

0.8×(4.3×1.25)

3.12+3.12×99

28.6×101-28.6

0.86×15.7-0.86×14.7

2.4×102

2.31×1.2×0.5

14-7.32-2.68

2.64+8.67+7.36+11.33

70÷28

(2.5-0.25)×0.4

9.16×1.5-0.5×9.16

3.6-3.6×0.5

63.4÷2.5÷0.4

4.9÷1.4

3.9÷(1.3×5)

(7.7+1.54)÷0.7

2.5×2.4

2.7÷45

15÷(0.15×0.4)

0.35×1.25×2×0.8

32.4×0.9+0.1×32.4

15÷0.25

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