巧算 1/2+1/3+2/3+1/4+2/43/4+1/5+2/5+3/5+4/5+···+1/100+2/100+···+99/100=?

问题描述:

巧算 1/2+1/3+2/3+1/4+2/43/4+1/5+2/5+3/5+4/5+···+1/100+2/100+···+99/100=?

运用公式:1/n+2/n+…+(n-1)/n=[1+2+3+…+(n-1)]/n=(n-1)/2 (n>=2,n为自然数)1/2+1/3+2/3+1/4+2/4+3/4+1/5+2/5+3/5+4/5+···+1/100+2/100+···+99/100=1/2+2/2+3/2+…+99)/2=(1+2+…+99)/2=4950...