A symbolic approach to the computation of the determinant of a matrix from the solution of an associated linear system of equations, proposed in 1988, was recently revived and made a method of practical choice. In many geometric applications (e.g. to computation of convex hulls), however, one needs only a single bit defining the sign of the determinant. In this case, there are more effective algorithms, which use some numerical techniques. One approach works for the computation of one or a few leading bits of the determinant or another algebraic predicate and relies on numerical version of Chinese remainder theorem. Another approach works only for the sign of matrix determinant. It is purely numerical and complements naturally the symbolic ones.