Let's break this into all our needed categories!
As we go up it keeps getting larger.
(For this exercise I'll ignore the 0s to save both of us time)
1. The number 1 has only a number, 1, in the ONES Place
2. The number 10 has a number, 1, in the TENS Place
3. The number 100 has a number, 1, in the HUNDREDS Place
4. The number 1,000 has a number, 1, in the THOUSANDS Place
5. The number 10,000 has a number, 1, in the TEN-THOUSANDS Place
6. The number 100,000 has a number, 1, in the HUNDRED-THOUSANDS Place
7. The number 1,000,000 has a number, 1, in the MILLIONS Place
8. The number 10,000,000 has a number, 1, in the TEN-MILLIONS Place
9. The number 100,000,000 has a number, 1, in the HUNDRED-MILLIONS Place
10. The number 1,000,000,000 has a number, 1, in the BILLIONS Place.
As for our number, you take the highest place value name, you have. So we see Three Hundred Nine Million. Whenever you see key place values like that you know you have the 100,000,000 setup to work with. The "Three Hundred" represents the amount millions there are. So 300 million. The 9 million is just going in the Million slot. So the number looks like: 309 Million. So the fully written out first bit looks like this:
309,000,000
Now we need to fill the rest.
Fifty-Eight Thousand.
The next place value after 309 million is the hundred thousands.
309,000,000
Because they didn't say hundred thousand anywhere in there we can assume that the hundred thousands place is empty. Next up is the ten thousands.
309,000,000
A lot of the times they won't say ten thousand. Instead they'll say some double digit number in the thousands. In this case they did that. 58 thousand looks like this:
58,000
So we just plop that right in the thousands and ten thousands spot.
309,058,000
Three Hundred Four. This is very similar to the millions. The hundred tells us we are dealing with the hundreds place. The four tells us we are dealing with the ones place, because if it was the tens place it would be forty (40).
So our final answer is:
309,058,304