numeric variable

Thanks Phil for your reply.

But if I take slide 1 (and assign 1), then take slide 2 (and assign 2), then go back to slide 1, I get a 1 in my meter (but it should be marked 2).

And what if I decide to take chapter 1, then 3, then 2 ? (the add a value seemed to be a good solution - only that it adds a value as many times as I visit the same slide).

Any other solution ?

Thanks, 

Chris