Numbers, such as 84, have two digits.  Each digit is a different place value.

The first digit is the tens' place.  It tells you that there are 8 tens in the number 84.

The right digit is the ones' place which is 4 in this example.  Therefore, there are 8 sets of 10, plus 4 ones in the number 84.

 

   8 4
   | |__ones' place
   |_________tens' place