Tensift · Ten cards. Four groups. One hidden rule.
Countries
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This page contains the answer to a past puzzle. Today’s puzzle is separate.
Australia · Brazil · Argentina · Canada · Mexico · United States · France · Germany · Italy · Spain
Find the scale of the question
Start with the four European countries. They form a plausible four-card row without needing a detail such as currency, language or population. Brazil and Argentina suggest a second geographic group. Together, those observations make a continent-based interpretation worth testing.
Australia then occupies the one-card row, leaving Canada, Mexico and the United States together. Count every group before committing: the useful evidence is that a single geographic convention accounts for all ten cards in exactly the required sizes.
Why language is a tempting wrong turn
Shared languages can connect some of these countries, but that hypothesis does not produce the same complete partition. A partial association is not enough: if your rule works for three cards and leaves several exceptions, compare it with a rule that handles the entire board.
Treat the one-card row as a cross-check, not your first certainty. Almost any country can be made unique by choosing a sufficiently specific fact. It becomes meaningful only when the same property organizes the other nine.
A note on geographic conventions
This puzzle uses Oceania and separates North America from South America. Other educational traditions count continents differently. Mexico belongs in the North America row here; “Latin America” is a different grouping and would change the problem.
The linked UN M49 table is a reference for geographic regions and country placement, not a claim that all its statistical subdivisions equal this puzzle’s four categories. Read the rule with the stated convention in mind rather than assuming every regional label is interchangeable.
The grouping
Each group is defined by a continent: Oceania has 1 item, South America has 2, North America has 3, and Europe has 4.
- 1 · Oceania
Australia
- 2 · South America
Brazil · Argentina
- 3 · North America
Canada · Mexico · United States
- 4 · Europe
France · Germany · Italy · Spain