Can someone tell me what is next in that 3 sequences?

Question

I'm looking at three sequences from the test at http://free.ultimaiq.net/nse.htm. I managed to answer 27 of the 30 questions, but I'm really curious about the other three.

Q6: 1001, 4524, 4299, 3984, ? -- here is something like 100 145 244 299 398 45+99+55+99 and the next one should be 398+65and+99 but its not

Q24: 50625, 1296, 8100, 3240, ? -- I only know that the answer is not an integer and there is a hint "think how you can arrive at an+2 given an+1 and an".

Q22: 38, 50, 22, 18, ?, ?

Answer 1

Q6:

The answer is 4354, which is +45,+99,+55,+99,+45,+99, so 443,542 splits into the 4-digit 4354.

Q24:

$50625=2^03^45^4$
$1296=2^43^45^0$
$8100=2^23^45^2$
$3240=2^33^45^1$

The power of $3$ stays constant, the powers of $2$ and $5$ are the average of the previous two, so the answer is $2^{2.5}3^45^{1.5}=5122.889809472774517838207541981$, although anything with 1dp or more seems to work.