Two extremely simple examples:
-If you have ten cards left in your deck and one of them is eternity, what are the odds you'll draw Eternity next turn?
Answer = (1/10 = 0.1 = 10%)
-If you play a quantum tower, what are the odds that it gives you 3 water quanta?
Answer = (1/12 * 1/12 * 1/12 = 1/1728 = 0.00058 = 0.058%)
A more complex example:
-If you have 13 pillars in a 30 card deck, what are the odds that you will draw at least three of them in your opening hand of seven cards?
Answer = This one's a little more work to figure out... but it turns out to be 67.4%. (The answer involves a cumulative hygeometric probability...
)