Few enigmatic puzzles [closed]

1. ?, 63264, 12825, 65121, 02420, 48409
2. REDYPS, Y = ?
3. 8, 33, 5 : X, II, ?
4. Gods in space (7 letters) =
5. 51151 = 8812, 22334 = 8459, 99111 = 2110910, 27772 = ?
• It seems that these puzzles are from the Neologic test, whose rules say "No discussing test items with others or posting your solutions elsewhere." No offence, but posting the question here seems to go against the spirit of that test. The author asks that the test should be discussed in their own forum.
– PDT
Feb 19 at 8:17

I'm stuck on #5 and haven't been able to solve it, but here's what I got for the rest:

#1 is

12481

because

It is the sequence of integer powers of two (1, 2, 4, 8, 16, 32, etc.) concatenated and split into 5 digit numbers.

#2 is

the letter I

because

Reversing the string of letters, we get SPYDER, which is SPIDER but the I is exchanged for Y. I remember this to be the answer to the sphinx riddle in Harry Potter and the Goblet of Fire, although I am not sure if that's significant in this puzzle.

#3 is

the letter O

because

X is the 24th letter of the alphabet. 8 x 3 = 24. I is the 9th letter of the alphabet, so II corresponds to 99. 33 x 3 = 99. Doing the same thing to 5, we get 5 x 3 = 15, and O is the 15th letter of the alphabet.

#4 is

PLANETS

because

They are named after Roman gods, and exist in space.

(I'm new to Puzzling SE and not quite sure if I'm supposed to put partial answers, so let me know if this is a bad post and I'll delete it!)

• For puzzles like this partial answers are more than fine, especially as you've got 4 out of 5! Feb 18 at 22:58
• Brilliant, try to figure out the 5th puzzle! Feb 19 at 6:17