It's a useful exercise to think about how much money pound;1 billion is.
If you earn pound;20,000 per year, how many years will it take to earn pound;1 billion? How many pound;100,000 houses will it buy? Can pupils do these sums without a calculator? Can they simplify them using standard form?
Ask them how long Britain's coastline is. The answer depends on the length of the ruler. The shorter the ruler, the longer your measurement will be.
This idea that as the scale of measurement gets smaller, the length gets bigger, is related to fractal curves and surfaces, so consideration of coastlines is a nice way to introduce fractals.