To solve the equation
\[ \frac{h^{450}}{h^n} = h^{215}, \]
we can use the property of exponents that states
\[ \frac{a^m}{a^n} = a^{m-n}. \]
Applying this property to our equation gives:
\[ h^{450-n} = h^{215}. \]
Since the bases are the same, we can set the exponents equal to each other:
\[ 450 - n = 215. \]
Now, we can solve for \(n\):
\[ 450 - 215 = n, \]
\[ n = 450 - 215 = 235. \]
Thus, the missing exponent \(n\) is
\[ \boxed{235}. \]