MathDB
2013 Team #4: Sum of real numbers

Source:

February 18, 2013
floor function

Problem Statement

Let a1a_1, a2a_2, a3a_3, a4a_4, a5a_5 be real numbers whose sum is 2020. Determine with proof the smallest possible value of 1ij5ai+aj. \displaystyle\sum_{1\le i \le j \le 5} \lfloor a_i + a_j \rfloor.