How do I enter fractions say 8 1/2 where the 1/2 becomes smaller asyou would do in Word

How do  I enter fractions say  8 1/2  where the 1/2 becomes smaller as you would  do in Word.Currently I use size 12 for main number and size 10 for the fraction.

Any suggestions? I am using Framemaker 9.

thanks

Joe