Whar is Time?#!#How to know time

A coin is tossed 20 times and head occurred 12 times. How many times did tail occur?

A coin is tossed three times and the outcomes are recorded. How many possible outcomes are three ? How many possible outcomes if the coin is tossed : Four times , Five times , n times ?

Evaluate : a times a times a times a times a times a times a

a times a times a times b times b times c times c times c times c times c