The US short scale for a billion billion (quintillion) is 1,000,000,000,000,000,000 (1 x 1018).
The short scale adds new number names by thousands (a billion is 1000 million).
On the long scale (European), a billion billion is 1 followed by 24 zeroes (1 x 1024).
1.52 billion written in numbers is 1,520,000,000
17.9 billion written out in numbers is 17,900,000,000
1,000 billion billion is: 1,000,000,000,000,000,000,000
Six billion = 6,000,000,000
15.8 billion = 15,800,000,000
153.4 billion = 153,400,000,000
3,900,000,000 is 3.9 billion.
2,280,000,000 = 2.28 billion
It is 27,638,000,000 = 27.638 billion
4.2 billion = 4,200,000,000
It is: 25,300,000,000 = 25.3 billion
It is: 900,000,000 = 0.9 billion