Notice the red, green and blue sequences that repeat?
Green is our units category
Blue is our tens category
Red is our hundreds category
Together, these make up the simple hierarchy of numbers (such as the number 527)
Repeated, we move into the units of thousands (green again!), tens of thousands (blue again because it's tens), and hundreds of thousands (red!). This is the thousands hierarchy.
The colors just repeat for each hierarchy in order:
And in elementary, the children learn about tenths, hundredths, thousandths, etc - the colors are the same but lighter, going backwards.