3/2+3/6+3/12+...+3/98*99+3/99*100
=3/1*2+3/2*3+3/3*4+...+3/98*99+3/99*100
=3(1-1/2+1/2-1/3+1/3-1/4+.+1/98-1/99+1/99-1/100)
=3(1-1/100)
=297/100
3/2+3/6+3/12+...+3/98*99+3/99*100
=3/1*2+3/2*3+3/3*4+...+3/98*99+3/99*100
=3(1-1/2+1/2-1/3+1/3-1/4+.+1/98-1/99+1/99-1/100)
=3(1-1/100)
=297/100