An ECDSA private key is simply a 256 bit integer between 0x1 and 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364140. So all you need to do is combine those random numbers so that the result is in that range. The result is your private keys. I'm pretty sure that however you combine those numbers will still be safe, so how you want to do it is up to you.
So if I multiply the 62 numbers together, would that work?
But if I add them together , won't that create a very weak key, a small number that is still in the range of computers that go through addresses 1 by 1? So isn't it important to have the key at the higher ends of the randomness.
An ECDSA private key is simply a 256 bit integer between 0x1 and 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364140.
There is a roughly 1 in 2^128 chance (not worth worrying about) of a random 256 bit key not falling in this range.
What would happen to a wallet program if this happened?
Well my key would only be 160 bit, so it would be even lower + I would check it later if the address that derives from it is BTC compatible.
I am asking about the private key's randomness here.