(I have minimal math skill and want to know how to even approach my problem)
In my board game, there are 7 "board" locations. Players likely have a preference/desire to interact with a specific location. Players are considering cards to play, where the cards affect one location. I need to calculate a weighted mechanical value for cards that offer 1 location / multiple locations / any locations for the single card effect to activate. For example: (screen capture). This shows that if a player is offered 4 specific locations to do something, there's a 57% chance than their desired location is offered.
I'd like to assign these rows a rating of "value". For example, being offered only 1 option is a "1" value. Being offered 7 options seems (at first glance) to be a 7 then, 7 times as useful as only 1 option. However, this isn't true. If your only need is to play location X and the 7-option card is 7x harder to play than the 1-option card, you would be better off considering 4 * 1 option cards (and odds are you would find Location X on one of these, 57%). The "value" rating should increase more slowly than flat multiplication, likely at an exponentially diminishing amount. The higher over 3.5 options you go, the less each additional option offered to you matters / adds value.
How would I calculate (based on the 1 / 7 being a 1 value) the diminishing returns on value for each additional option?