1/3*6+1/6*9+1/9*12+.+1/300*303

1/3*6+1/6*9+1/9*12+.+1/300*303
=（1/3-1/6+1/6-1/9+1/9-1/12+……+1/300-1/303）÷3
=（1/3-1/303）÷3
=100/303÷3
=100/909