Combination is not the term, I guess you mean **permutations **and it is **50! = 3.04140932*10^64** which you can't store it anywhere not just because of capacity *problems* but also because of the time required for writing them, it would take billions times the galaxy's age for a multiple penta byte per second write operation, I suppose.

That's assuming you only have 50 characters available in total (over a string with the length of 50) of which each character can only be used once.

I'm afraid mfyilmaz is a bit closer to the truth.

Still none of you guys have answered OP's question

Using WIF (as requested by OP) would add unnecessary overhead to storing the private keys, so we're gonna save some storage and will just go with barebone private keys.

So taking the numbers as calculated by mfyilmaz and bob123:

2^256 = 1.15 * 10^77

You get 1.15 * 10^77 possible keys with a size of 2^256 bits (= 32 bytes) each so you get 32 * 1.15 * 10^77 bytes for storing all possible combinations of a 256 bit key.

32 * 1.15 * 10^77 equals 48 * 10^77 bytes which is 48 * 10 ^

~~68~~ 65 Terabytes, ie. 48,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

~~,000~~ Terabytes or roughly the amount of data you could store using 2 X chinese kids, an abacus and 30 minutes.

(edit: Thirdspace's post reminded me that Tera = 10^12 not 10^9)