Approximating with powers of 10

In $2014$, the population of the United States was about $318{,}900{,}000$ people. **Choose the best approximation of the United States population in $2014$.** [[☃ radio 1]] In $2014$, the population of the world was about $7{,}125{,}000{,}000$ people. **Choose the best approximation of the world population in $2014$.** [[☃ radio 2]] **Approximately how many times as large was the world population as the United States population in $2014$?** [[☃ radio 3]]