Probability - #offgrid

full text - Repost: Probability (from https://ift.tt/ZkhmTAe, Probability)

Suppose that you have an alphabet of 26 letters. A letter in the alphabet is said to be fixed if the encryption of the letter is the letter itself. How many simple substitution ciphers are there that leavea) No letters fixed?b) At least one letter fixed?c) Exactly one letter fixed?d) At least two letters fixed?

---

---

Mining:
Bitcoin, Cryptotab browser - Pi Network cloud PHONE MINING
Fone, cloud PHONE MINING cod. dhvd1dkx - Mintme, PC PHONE MINING

---

Exchanges:
Coinbase.com - Stex.com - Probit.com

---

Donations:
Done crypto