jmc

Notice that: $9\cdot 4=36$ and $3+6=9=9\cdot 1$ $99\cdot 44=4356$ and $4+5+3+6=18=9\cdot 2$ So the sum of the digits of $x$ 9s times $x$ 4s is simply $x\cdot 9$ (Try to find the proof that it works for all values of $x$ ~MATHWIZARD10). Therefore the answer is $94\cdot 9=\boxed{846}$