What system are our numbers based on?

The numbers in use in the United States and everywhere around the world are part of the decimal system of numbers. It is a base 10 system, and the units are all powers of 10.

The number farthest to the right before any decimal point is the ones' place. The next number to the left is the tens' place, the next is the hundreds' place and the next is the thousands' place. Each place to the left is 10 times the value of the place to the right. To the right of the decimal point is the tenths' place, followed by the hundredths, thousandths, ten-thousandths and so forth.