JAMB 2012 · UTME · Q24

Given that $I_3$ is the unit matrix of order 3, find $|I_3|$ .

Worked solution (try it first)

$I_3$ has 1s on the leading diagonal and 0s everywhere else.
For a matrix with zeros off the diagonal, the determinant is the product of the diagonal entries: $1 \times 1 \times 1 = 1$ , option C.