Many things in life are simpler when you only need to be within 5%:
- Pi is pretty much 3
- Water weighs pretty much 8 pounds a gallon
- A quart is pretty much a liter (and a gallon, 4 liters)
- A year has pretty much 360 days, and pretty much 31 million seconds
- The speed of light is pretty much 300,000 km/s, which is pretty much one foot/nanosecond
Of course, there’s even more things that get more convenient when you have 10% or 20% to work with… -m