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Combinatorics 7.0/10

Sum of the Minima

For each of the C(10, 3) = 120 three-element subsets of {1, 2, ..., 10}, write down its smallest element. What is the sum of all 120 numbers written? Give an integer.

Related problems & prerequisites

Worth solving first

Source: Classic counting exercise in wide circulation; no traceable original source. Statement written for AxiomIQ.