# One in a Million V. One in a Billion

**Discrete Mathematics**Level 2

If you had a fair coin, that is one that flips heads and tails evenly, and flipped it 20 times in a row, the odds that all twenty of those flips will be heads is about \(1 \text{ in a } 1,000,000\).

If you kept flipping and kept turning up heads, how much more flips of heads would you have to get to for the odds to be at least \(1 \text{ in a } 1,000,000,000\)?