I like the concept.

However the UI is a little confusing (on mobile anyway).

I might suggest you don't present the pre-set range values, as it makes it a lot easier.

Have you considered - perhaps in a way to gamify it a bit more - giving a first hint, and hiding the next 3 unless the player asks for them? It would add an element of 'getting it in 1 go' etc. I'd imagine one or two-shot winners are also more likely to share their results. More potential for your app to go viral.