15 billion is correct unless there is some reason to capitalize the word billion, perhaps in a title.
The correct spelling is Billion.
15
one thousand million=15 billion 1 billion/ 15 billion = 1/15= 0.0666
15
percentage = 6.67%% rate:= 1 billion /15 billion * 100%= 0.0667 * 100%= 6.67%
270.2667
1.5 billion.
As a number it is: 17,900,000,000 = 17.9 billion
15% of 7 billion: = 15% * 7000000000 = 0.15 * 7000000000 = 1,050,000,000
60,000,000,000 +20,000,000,000 + 15,000,000,000 + 5,000,000,000 = 100,000,000,000
2.3333
how to write 5.1 billion