Question

1／3+1／8+1／15+……+1／120=?答对有奖

Answer 1

1/3+1/8+1/15+.+1/120

=1/(1*3)+1/(2*4)+1/(3*5)+……+1/(10*12)

=1/2*[(1/1-1/3)+(1/2-1/4)+(1/3-1/5)+……+(1/10-1/12)]

=1/2*(1+1/2-1/11-1/12)

=1/2*175/132

=175/264