Upon clicking START you will be presented with a 5×5 table of World countries. The object of the quiz is to pair up countries two at a time which have the closest ratio of their populations (including dependent territories).

Single click on a country’s text and it will highlight red. To choose the other country of the pair click another country’s text. Also, you can re-click on the first country to deselect it. The ratio of the larger country’s population to the smaller country’s will be shown and you will get up to 100 points. 100 points corresponds to the smallest population ratio, 0 points to the largest ratios (there may be multiple pairs with 0 if they are far away from the smallest ratio). Those two countries will then be replaced with their score and you will now choose the pair with the smallest population ratio from the remaining 23 countries which have been adjusted to have 100 and 0 corresponding to the ratios among those 23, and so on until you run out of time or complete 12 pairs of countries leaving one left.

You get a 100 point bonus for completing all 12 pairs within 5 minutes, making for a total possible point total of 2500.