If each element of a second order determinant is either zero or one, what is the probability that the value of determinant is non-negative?

In a 2×2 determinant there are 4 elements and each element can take 2 values. So, total number of 2×2 determinants with elements 0 and 1 is 2⁴ = 16. Out of these determinants the values of the following determinants are negative.

Hence, required probability = 13/16