a billion dollars...waste

It's difficult to get my head around this billion dollar thing. The Germans call it Milliards...instead of Billion. I believe a billion is is 1,000 Millions.
The recent in Toronto Canada G8 &  G20 event  apparently cost over a billion dollars to police. Including local ,provincial, federal RCMP...army?...all together a billion dollars cost to police this event.
Unless I'm out a decimal point...that's the equivalent of the cost of building 4,000 homes at $250,000 each or over 20,000 seniors residences at $50,000 each. What a waste.
Other billion dollar efforts with little or nothing to show for are:

The long rifle gun registry efforts, money wasted by the last federal liberal government ...

The E-Health registry attempt, Ontario Provincial government waste by the current Ontario Liberal government.