Question

Tinh nhanh :

a, 321 + { 15 + [ 30 +  (-321) ] }

b, ( 2016 + 432 ) + [ 168 + (-2016) ]

Answer 1

a)=321+15+30+(-321)

=[321+(-321)]+(15+30)

=0+45=45

b)=2016+432+168+(-2016)

=[2016+(-2016)]+(432+168)

=0+600=600

Answer 2

a)321+{15+[30+(-321)]}=[321+(-321)]+(15+30)=0+45=45

b)(2016+432)+[168+(-2016)]=[2016+(-2016)]+(432+168)=0+600=600