What is the product of (21)\begin{pmatrix} 2 & 1 \end{pmatrix}(21) and (34)\begin{pmatrix} 3 \\ 4 \end{pmatrix}(34)?
(64)\begin{pmatrix} 6 \\ 4 \end{pmatrix}(64)
101010
(64)\begin{pmatrix} 6 & 4 \end{pmatrix}(64)
777