There are five numbers 1,2,3,4,5. If you want to find any two of them, the sum of them is the probability of even numbers
There are 5 × 4 △ 2 = 10 methods, among which there are 4 kinds of even sum terms (1,3), (1,5), (3,5), (2,4), so the probability is 4 △ 10 = 0.4