a) 22.85 + 15.22 - 20200

= 4.85 + 15.4 – 1

= 4.(85 + 15) – 1

= 4.100 – 1

= 400 – 1

= 399

b) 50 + [65 - (9 - 4)2]

= 50 +

= 50 + [65 – 25]

= 50 + 40

= 90

c) (39 - 19) : (-2) + (34 - 22).5

= 20 : (-2) + 12.5

= -10 + 60

= 50

d) 123.456 + 456.321 – 256.444

= 456.(123 + 321) – 256.444

= 456.444 – 256.444

= 444.(456 – 256)

= 444

a) 22.85 + 15.22 - 20200= 4.85 + 15.4 – 1= 4.(85 + 15) – 1= 4.100 – 1= 400 – 1= 399

b) 50 + [65 - (9 - 4)2]= 50 += 50 + [65 – 25]= 50 + 40= 90

c) (39 - 19) : (-2) + (34 - 22).5= 20 : (-2) + 12.5= -10 + 60

= 50d) 123.456 + 456.321 – 256.444= 456.(123 + 321) – 256.444=456.444 – 256.444= 444.(456 – 256)= 444

Câu 2: 

a: =2200-20200=-18000

d)123 x 456+456 x 321 - 256 x444

= ( 123 + 321) x456 - 256 x 444

= 444 x456 -256 x444

=200 x 444 

=88800

\(\text{c) (39 -19) : (-2) + (34 - 22).5}\\ =20:\left(-2\right)+12.5\\ =\left(-10\right)+60=50\)

\(\text{d) 123.456 + 456.321 – 256.444}\\ =456.\left(123-256+444\right)\\ =456.311=141816\)

c, (39 -19) : (-2) + (34 - 22).5

= 20: (-2) + 12.5 =(-10 )+ 60= 50

d, 123.456 + 456.321 – 256.444

=456.(123+321) - 256.444

= 456. 444 -256. 444

=444.(456 - 256)= 444.200 =88800

a: =6^2-15*2

=36-30=6

b: =3*25+15*4-3

=72+60

=132

c: =25*2+5

=50+5

=55

d: =5+12=17

e: =7^2(15-5)=49*10=490

f: =4^3*125-125:25

=1000-5

=995

f: =20:4+5

=5+5

=10

e: =125-100=25

tự tính

a) \(\dfrac{3}{10}\)

b) \(\dfrac{9}{28}\)

c) \(\dfrac{88}{195}\)

a) 675+125+723-23

=(675+125)+(723-23)

=800+700

=1500

b) 325.40+325.60-25.100

=325.(40+60)-25.100

=325.100-25.100

=100.(325-25)

=100.300

=30000

c) 80+[37-(32+23)]

=80+(37-55)

=80-18

=62

d) 22.85+15.22-20200

=22.(85+15)-20200

=22.100-20200

=2200-20200

=-18000

A. 122

B.256

C.23

e: \(=128-\left[68+8\cdot4\right]:4=128-25=103\)

\(a.3.5^2+15.2^2-26:2\)                     \(b.5^3.2-100:4+2^3.5\)

\(=75+60-13\)                                  \(=250-25+40\)   

\(=135+13=148\)                                \(=265\)

\(c.6^2:9+50.2-3^3.3\)                \(d.2345-1000:\left[19-2.\left(21-18\right)^2\right]\)

\(=4+100-81\)                            \(=2345-1000:\left[19-2.3^2\right]\)

\(=23\)                                            \(=2345-1000:\left[19-18\right]\)

                                                    \(=2345-1000:1\)

                                                    \(=2345-1000=1345\)

\(e.128-\left[68+8.\left(37-35\right)^2\right]:4\)               

\(=128-\left[68+8.2^2\right]:4\)

\(=128-\left[68+32\right]:4\)

\(=128-100:4\)

\(=128-25=103\)

\(f.568-\left\{5.\left[143-\left(4-1\right)^2\right]+10\right\}:10\)

\(=568-\left\{5.\left[143-3^2\right]+10\right\}:10\)

\(=568-\left\{5.134+10\right\}:10\)

\(=568-\left\{670+10\right\}:10\)

\(=568-680:10\)

\(=568-68=500\)

Bài 2: Tính nhanh

a) 29 + 132 + 237 + 868 + 3

 = 29+(132+858)+(237+3)

=29+990+240

=1259

29+132+237+868+3

29+(132+868)+(237+3)

29+1000+240

29+(1000+240)

29+1240

1269

bài 2 :

a) 29 + 132 + 237 + 868 + 3

= 29 +(132 + 868)+(237 + 3)

= 29 + 1000 + 240

=1269

b) 35 . 34 + 35 . 86 + 65 . 75 + 65 . 5
= 35 .(34 + 86)+ 65 .(75 + 5)

= 35 . 120 + 65 . 80

= 4200 + 5200

= 9400

c) 3 . 25 . 8 + 4 . 37 . 6 + 2 . 38 .12

khum bít làm hehe

d) 12 . 53 + 53 . 172 - 53 . 84

= 53 . (12 + 172 - 84)

= 53 . 100

= 5300

Bài 3:

a) 4 . 52 - 18 : 32 hình như câu này sai đề

b) 32 . 22 - 32 . 19

= 32 . (22 - 19)

= 32 . 3

= 96