The Decimal Number System
The decimal numbering system uses ten numbers (0,1,2,3,4,5,6,7,8,9) and the decimal point of course. From these ten numbers we can express all the measurements we need. Another way of saying this is that we have a "base 10" numbering system. The order in which we write these numbers is extremely important because each column has a different value or place value. Having a decimal point makes this system very flexible.
The example above is a decimal that contains a whole number plus tenths and hundredths etc. The number is one thousand, two hundred and thirty four and five tenths, six hundredths and seven thousandths. The decimal fraction or .567 is often pronounced as five hundred and sixty seven thousandths. There is a '1' in the thousands column, a '2' in the hundreds column, a '3' in the tens column, a '4' in the units or one's column, a '5' in the tenths column, a '6' in the hundredths column and finally a '7' in the thousandths column.
Another thing to notice here are the green arrows. Going left, each place value is 10 times larger and going right each place value is 10 times smaller. Numbers to the left of the decimal are greater than 1 and numbers to the right of the decimal are less than 1.