Question

If number of numbers, greater than $400,000$ that can be formed by using the digits $0,2,2,4,4,5$ is $10x^2$ then positive value of $x$ is

Answer 1

Number of digits $:6$

$3\times 5\times \underset{any4}{4}\times \underset{any3}{3}\times \underset{any2}{2}\times \underset{lentme}{1}=360=10x^{2}given$

$\left\{\begin{array}{cc}4& 0\\ 4& 2\\ 5& 2\end{array}\right\}$

$\Rightarrow x=6$