Question

1++2+3+4+5+6+7+8.+241+242+243等于多少 ?说说道理

Answer 1

1++2+3+4+5+6+7+8.+241+242+243

=1/2[(1++2+3+4+5+6+7+8.+241+242+243)+(243+243+241+……+3+2+1)]

=1/2[(1+243)+(2+242)+(3+241)+……+(241+3)+(242+2)+(243+1)]

=1/2*(244*243)

=122*243

=29646