Once you can write a chance as a fraction, the world is full of them — and the same idea runs both ways: count outcomes to find a chance, or start from a chance to work out the outcomes.
Reading the Everyday Ones
A raffle sells 40 tickets and you buy 5: your chance of the one prize is 5/40 = 1/8 = 12.5%. A forecast of "70% chance of rain" is just 7/10 dressed as a percentage. A board game where 2 of 8 spinner slots win gives you 2/8 = 1/4 per spin. Every one is favourable ÷ total — only the costume changes.
Working Backwards
Sometimes you're given the chance and asked to build for it. "Design an 8-section spinner so brass has probability 3/8." Start from P = favourable ÷ 8 = 3/8, so favourable must be 3 — you colour three sections brass. Switch to the "design a spinner" tab and slide until your fraction matches the target; the maths you ran forwards in rung 2, you're now running in reverse.
Why This Is the Finish Line
Counting slices was the "aha". The three-move method made it quick. Knowing the traps kept it honest. But reading a real forecast or raffle, and designing something to a target chance — that's the bit that shows up when you're sizing up a game, a bet or an exam question. That's mastery.