To find the inverse of a square matrix, enter it and click on Inverse. The inverse will appear at the bottom center.
Because of rounding off, if you multiply a matrix by its inverse, you may not get exactly the Identity matrix (one on the diagonal, 0 everywhere else).
The inverse of a matrix is only defined for a square matrix, that is for a matrix with the same number of rows and columns.
Even a square matrix will have no inverse if its determinant is zero.