Multiply, add, subtract, multiply by a number, transpose a matrix or matrices. Store the result in a new variable.
Also, see the rank and determinant of the matrices. When adding an entry to a matrix, expressions such as (2+1/2)^(1/3) are allowed.

With the paid version of this app, The Matrix App PRO, also compute the inverse, eigenvalues (real and complex), eigenvectors, and find LU, Cholesky, QR and SVD decompositions.