\[\sqrt{10 + \sqrt{4 + \sqrt{x}}} = 4\]
\[10 + \sqrt{4 + \sqrt{x}} = 16\ \ \]
\[\sqrt{4 + \sqrt{x}} = 6\]
\[4 + \sqrt{x} = 36\]
\[\sqrt{x} = 32\ \ \]
\[x = 1024.\]