Question

Tính nhanh: 3+6+12+24+48+96+192

Answer 1

=9+12+24+48+96+192

=21+24+48+96+192

=45+144+192

=189+192

=381

Answer 2

= 381 

Answer 3

A=3+6+12+24+48+96+192

A.2=6+12+24+48+96+192+384

A.2 - A=(6+12+24+48+96+192+384) - (3+6+12+24+48+96+192)

A=384 - 3

A=381