The answer is 2.1 US dollars,
Yes it is the same thing ! :)
Start from the right-most 7, and go one digit to the left each time:
7 - units place
7 - tens place
7 - hundreds place
3 - thousands place
2 - ten-thousands place
6 - hundred-thousands place
5 - millions place
4 - ten-millions place <----- answer to this question
1 - hundred-millions place
8 - billions place
0 - ten-billions place
9 - hundred billions place
The ten-millions place is the 4.
