0.0311
No, "billion" should not be capitalized in a sentence like "45 billion dollars." It is only capitalized if it is part of a proper noun or at the beginning of a sentence.
Look between 45 and 54
45% = 9⁄20
1 billion minutes = 1,901.32 years
0.0222
45 billion is 5 billion away from 50 billion. That is not very close at all, but it is closer to 50 billion than it is to 50 million, for example.
0.0222
45 billion.
45 books to 35 books would turn out to look like 45/35. Both numbers are divisible by 5, so in lowest terms it would be 9/7.
45 15,3 5,3,3
45 15,3 5,3,3