Let the digits of the required number be x and y.
Now, the required number is 10x + y.According to the question,
10x + y = 4(x + y)
So,6x − 3y = 0
\[\Rightarrow\]2x − y = 0
\[x = \frac{y}{2}\] .....(1)
Also,
10x + y = 3xy .....(2)
From (1) and (2), we get
\[10\left( \frac{y}{2} \right) + y = 3\left( \frac{y}{2} \right)y\]\[ \Rightarrow 5y + y = \frac{3}{2} y^2 \]
\[ \Rightarrow 6y = \frac{3}{2} y^2 \]
\[\Rightarrow y^2 - 4y = 0\]\[ \Rightarrow y(y - 4) = 0\]
\[ \Rightarrow y = 0, 4\]
So, x = 0 for y = 0 and x = 2 for y = 4.
Hence, the required number is 24.