1/1*4+1/4*7+1/7*10+1/10*13+...+1/94*97+1/97*100
=1/3(1-1/4)+1/3(1/4-1/7)+1/3(1/7-1/10)+.+1/3(1/97-1/100)
=1/3(1-1/4+1/4-1/7+1/7-1/10+...+1/97-1/100)
=1/3(1-1/100)
=33/100