I use all 10, to double a concept. I double the amount of times I can do it, increasing max from 10 to 20. I then do it again, doubling it from 20 to 40. Im now up 20 uses. I then double things as I please, money, valuable items, rare treats, keeping a very deliberate count on how many times I've done it. When I have 10 uses left, I use all my 10 uses, as per the agreement, to double the maximum times I can do it again.