We can do this by multiplying each element of $\mathbf{A}$ and $\mathbf{B}$ by 2.
For $\mathbf{A}$, we get:
$$
2\mathbf{A}=\left[\begin{array}{llll}
2*2 & 2*3 & 2*1 & 2*9 \\
2*1 & 2*0 & 2*5 & 2*0 \\
2*6 & 2*7 & 2*8 & 2*4
\end{array}\right] =
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