3分之1加15分之1加35分之1加63分之1等于多少

1/3+1/15+1/35+1/63
=1/(1×3)+1/(3×5)+1/(5×7)+1/(7×)
=1/2×[2/(1×3)+2/(3×5)+2/(5×7)+2/(7×)]
=1/2×(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9)
=1/2×(1-1/9)
=4/9