Creating a multi-quantity listing

[qj1950]

I am trying to create a multi-quantity listing.  Several years ago it was very clear on how to do it, but now I'm not sure how to do it.  Previously I was able to "add" the additional weight for each additional item being purchased to create the proper weight for the shipping calculation.  That is no longer there, but I see "calculated shipping rule" that has a subtraction of weight choice.  What is it subtracting from?  Is a subtraction done for number of items over 1 being purchase?  Any help would be appreciated!

[disneyshopper]

I use Calculated shipping on all of my listings, giving a discount for combined shipping.  The rule I use is to Add the weights.