If you toss 9 fair coins, in how many ways can you obtain at least one head?
There are different ways of obtaining at least one head.

Step 1 ：Let's denote the total number of outcomes when tossing 9 fair coins as \(total\_outcomes\). Each coin has 2 possible outcomes (head or tail) and there are 9 coins. So, \(total\_outcomes = 2^9 = 512\).

Step 2 ：The only way to not get at least one head is if all coins land on tails. There is only 1 way for this to happen. Let's denote this as \(ways\_no\_heads = 1\).

Step 3 ：The number of ways to get at least one head is the total number of outcomes minus the one way to get no heads. So, \(ways\_at\_least\_one\_head = total\_outcomes - ways\_no\_heads = 511\).

Step 4 ：Final Answer: The number of ways to get at least one head when tossing 9 fair coins is \(\boxed{511}\).