Toán Lớp 6: : Tính một cách hợp lí:
a) 387 + ( – 224) + ( – 87); b) ( – 75) + 329 + ( – 25)
c) 11 + ( – 13) + 15 + ( – 17); d) ( – 21) + 24 + ( – 27) + 31
“nhanh nha mn ==” e cần gấp ”
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Toán Lớp 6: : Tính một cách hợp lí:
a) 387 + ( – 224) + ( – 87); b) ( – 75) + 329 + ( – 25)
c) 11 + ( – 13) + 15 + ( – 17); d) ( – 21) + 24 + ( – 27) + 31
“nhanh nha mn ==” e cần gấp ”
Comments ( 2 )
a) 387 + ( -224 ) + ( -87)
= [387 + ( -87 )] + ( -224 )
= 300 + ( -224 )
76
b) ( -75 ) + 329 + ( -25 )
= [( -75 ) + ( -25 )] + 329
= -100 + 329
= 229
c) 11 + ( -13 ) +15 + ( -17)
= [( -13 ) + ( -17)] + 11 + 15
= ( -30 ) + 26
= ( -4 )
d) ( -21 ) + 24 + ( -27 ) +31
= [( -21 ) + ( -27 )] + ( 24 + 31 )
= ( -48) + 55
7