Question

2*2/1*3+4*4/3*5+6*6/5*7+8*8/7*9+10*10/9*11+12*12/11*13=

Answer 1

2*2/1*3+4*4/3*5+6*6/5*7+8*8/7*9+10*10/9*11+12*12/11*13

=1+1/3+1+1/3*5+1+1/5*7+1+1/7*9+1+1/9*11+1+1/11*13

=6+(1/2)*(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13)

=6+(1/2)*(1-1/13)

=6+6/13

=6又6/13