First choose any South America 50K+ city by entering it and choosing it in the drop-down box. Then, name the largest 50K+ South America city in each 50km circle/ring as the rings expand outward from your city of choice. The first circle will include your city of choice as a possible answer if it is the largest 50K+ city in that area.

When you run out of time or end the quiz, you will see the current ring’s correct answer at right (under ‘Answer Stats’ by your coordinates).

For example, if you choose ‘Sao Paulo, Brazil’ – you will be shown a circle of radius 50km centered at Sao Paulo. Naming the largest city in this circle (Sao Paulo in this case) will cause another ‘ring’ of radius 50km to appear outside that circle. You now need to name the largest 50K+ South American city in that ring (but not within any previous circles/rings). If a city is not within the next ring of that distance, the ring will keep expanding by that distance until a city falls within it. So if a city doesn’t fall within 50-100km, it will expand to be a 50-150km ring, then 50-200km and so on until a qualifying city is found within the ring.