a)

349 + 602 + 651 + 398

= (349 + 651 ) + (602 + 398)

= 1000 + 1000

= 2000

b) 

3145 - 246 + 2347 - 145 + 4246 - 347

= (3145 - 145) + (4246 - 246) + (2347 - 347)

= 3000 + 4000 + 2000

= 7000 + 2000

= 9000

\(349+602+651+398\)

\(=\left(349+651\right)+\left(602+398\right)\)

\(=1000+1000\)

\(=2000\)

_____

\(3145-246+2347-145+4246-347\)

\(=\left(3145-145\right)+\left(2347-247\right)+\left(4246-246\right)\)

\(=3000+2000+4000\)

\(=9000\)

\(349+602+651+398=\left(349+651\right)+\left(602+398\right)=1000+1000=2000\)\(3145-246+2347-145+4246-347=\left(3145-145\right)+\left(4246-246\right)+\left(2347-347\right)=3000+4000+2000=9000\)

3145 - 246 + 2347 - 145 + 4246 - 347

=9000

chúc hok tốt

=9000

k mình nha!!

3145 - 246 + 2347 - 145 + 4246 - 347

= (3145 - 145) + (4246 - 246) + (2347-347)

=      3000        +       4000      +      2000

=                         9000

3145 - 246 + 2347 - 145 + 4246 - 347

= (3145 - 145) + (4246 - 246) + (2347 - 347)

= 3000 + 4000 + 2000

= 9000

3145-246+2347-145+4246-347

=(3145-145)+(2347-347)+((-246)+4246)

=3000+2000+4000

=5000+4000

=9000

a.(4276+5724)+(2357+7643)

=10000           +  10000

=20000

b.câu này không biết:)))

c.câu này cũng không biết :)))

a)4276+2357+5724+7643
= (4276+5724)+(2357+7643)
= 1000+1000
= 2000
b)3145-246+2347-145+4246-347
= (3145-145)+(4246-246)+(2347-347)
= 3000+4000+2000
= 9000
c)(45-5x9)x2x3x4x5x6x7x8x9
= (45-45)x2x3x4x5x6x7x8x9
=0x2x3x4x5x6x7x8x9
=0

c.(45-5x9)x2x3x4x5x6x7x8x9

=(45-45)x2x3x4x5x6x7x8x9

=0x2x3x4x5x6x7x8x9

=0

thui nha=)))

=(3145-145)+(4246-246)+(2347-347)

=3000         +4000          +2000

=                  9000

3145−246 + 2347−145 + 4246−347

= ( 3145 - 145 ) + ( 4246 - 246 ) + ( 2347 - 347 )

=   3000 + 4000 + 2000

=       7000+ 2000 = 9000

(3145-145) + (4246- 246) + (2347 - 347)

= 3000 + 4000+ 2000

= 9000

a) 815 – 23 – 77 +185 = (815 + 185) – (23+77) = 1000 – 100 = 900

b) 3145 – 246 + 2347 – 145 + 4246 – 347

= (3145-145) + (4246 – 246) + (2347 – 347)

= 3000 + 4000 + 2000 = 9000

c) (2018:1 – 2018.1):(2018.2008+2018.2002) = 0 : (2018.2008+2018.2002) = 0

d) (9 – 8 – 7 – 6 – … – 2 – 1).(500.9 – 250.18)

= (9 – 8 – 7 – 6 – … – 2 – 1).(500.9 – 250.2.9)

= (9 – 8 – 7 – 6 – … – 2 – 1).(500.9 – 500.9)

= (9 – 8 – 7 – 6 – … – 2 – 1).0 = 0

b: =2376-376+3425-42

=2000+3383

=5383

c: =3145-145+246+4246+2347-347

=3000+2000+4492

=9492

e: =(72-72):A=0

3145-246+2347-145+4246-347

=(3145-145)+(2347-347)+(4246-246)

=3000+2000+4000=9000

minh chi lam dk câu ý thui

Mình ko biết làm vì mình lớp ??????