Exactly as in the question: 1.351 billion.
Sixteen point two billion is how I would write it.
You would write it as 125,000,000,000
6.9 billion as a number would be 6,900,000,000. To write it out without digits it would be six billion and nine hundred million.
I would write it as in the question.
To write one billion three million, you would write out the number 1,003,000,000.
Sixteen point two billion is how I would write it.
Since you asked how I would write the number, the answer is 1031.
You would write it as 125,000,000,000
6.9 billion as a number would be 6,900,000,000. To write it out without digits it would be six billion and nine hundred million.
You would write it as 20,750,000,000. Twenty billion, seven hundred fifty million.
I would write it as in the question.
To write one billion three million, you would write out the number 1,003,000,000.
4.6 billion = 4,600,000,000
4,500,000,000
1,760,000,000
1,000,100,000,000
147,000,000,000