I know how it works – iMind Reader! Review

When you pick a number and subtract is as the rules say it has an icon or the only possible answers, every 9th one is the only possible ones, the bottom ones are blocked of mainly because they aren't possible answers. So every time it just equals one of the numbers, the symbol changes every time to not make you suspicious. Hope that helped explain it :)
Review by chopperteddy on iMind Reader!.