Question

Tính nhanh:

  9 + 6 + 3 + 1 + 8 + 7 + 2 + 4

Answer 1

9 + 6 + 3 + 1 + 8 + 7 + 2 + 4 

= ( 9 + 1 ) + ( 6 + 4 ) + ( 7 + 3 ) + ( 8 + 2 )

= 10 x 4

= 40

Answer 2

9+6+3+1+8+7+2+4

=(9+1)+(6+4)+(3+7)+(8+2)

=10+10+10+10

=10x4

=40