Ammonia has a pH of approximately 11, whereas urine has a pH of approximately 6. How many more times acidic is urine than ammonia?

Each time you move up the pH scale, you multiply the value by 10. So in this case, going from 6 to 11 is five steps up the scale—from 6 to 7, from 7 to 8, and so on. Therefore, you need 5 zeros, or 100,000.