A billion is a thousand million.
A billion looks like this: 1,000,000,000
So 200 billion looks like this: 200,000,000,000
Four hundred million looks like this: 400,000,000
So what had you asked for?
200,400,000,000. That's an awful lot of digits. If you had this amount of money in pounds, you'd be the richest person in the world by a country mile.
