HELP: How to - FORMULA SEQUENCE

Hello I have a formula that says...

=SUM(1/30*100) in cell B2

in C2, I want it to say =SUM(2/30*100), than D2, =SUM(3/30*100), until I have reached =SUM(30/30*100)

How can I do this QUICKLY without having to retype it all 30 times!?

I know that if you put for example in cell A1, number 1, than A2 number 2, A3, number 3 and highlight them all. You can than use the little + symbol at the bottom right corner of the highlighted cells to DRAG in a direction to make it AUTO-FILL in number sequence, 1, 2, 3, 4, 5, etc


Now I did manually fill out B2, C2, D2 but when I select them and drag, the formula does NOT change in sequence at all, it just COPYs itself three times.
What I mean by that is: =SUM(1/30*100), =SUM(2/30*100), =SUM(3/30*100) simply appear in cell B2, C2, D2... Than the SAME outcomes in E2, F2, G2... H2, I2, J2 etc...


I hope you understand what I am trying to say.

=columns($B2:B2)/30*100
enter the formula in "B2" and copy the formula from "B2" and paste towards right