Digits -- Value By Place

The value of a digit depends upon the position of the digit in the number.

In the number 8 the digit 8 simply tells us that the number of units is 8.

In the number 27 the digit 7 tells us the number of units
whilst the digit 2 tells us the number of tens thus the value of the 2 is 20.

In the number 456 the digit 6 tells us the number of units,
the digit 5 tells us the number of tens thus the value of the 5 is 50
and the digit 4 tells us the number of hundreds thus the value of the 4 is 400.