349+602+651+398=2000
3145-246+2347-145+4246-374=8973
a) 349 + 602 + 651+398
= ( 349 + 651 ) + ( 602 + 398 )
= 1000 + 1000
= 2000
a) 349+602+651+398
= ( 349 + 651) + (602 + 398)
=1000+ 1000
=2000
b )3145-246+2347-145+4246-374
=( 3145 - 145 ) + ( 4246-246)+ ( 2347- 347)
= 3000 + 4000 + 2000
= 9000
a) 349 + 62 + 651 +398 = ( 349 + 651 ) + ( 398 + 62 ) = 1000 + 460 = 146
a.349+602+651+398
=(349+651)+(602+398)
=1000+1000
=2000
b.3145-246+2347-145+4246-374
=(3145-145)+(4246-246)+(2347-347)
=3000+4000+2000
=9000
a,349+602+651+398
=(349+651)+(602+398)
=1000+1000
=2000
b,3145-246+2347-145+4246-374
=(3145-145)+(4246-246)+2347-374
=3000+4000+1973
=7000+1973
=8973
a)349+602+651+398
=(349+651)+(602+398)
=1000+1000
=2000
b)Mình nghỉ câu này ko nhanh đc
a , 349 + 602 + 651 + 398 = ( 349 + 651 ) + ( 602 + 398 )
= 1000 + 1000
= 2000
b, 3145-246+2347-145+4246-374 = 3145-145+(-246+4246)+(2347-347)
=3000+4000+2000
=9000
a) 349+602+651+398
= ( 349 + 651) + (602 + 398)
=1000+ 1000
=2000
b )3145-246+2347-145+4246-374
=( 3145 - 145 ) + ( 4246-246)+ ( 2347- 347)
= 3000 + 4000 + 2000
= 9000