Print the pdf and cut the rows apart with a scissors. preferably cut it along the top line of the row that has the dice numbers on it. 
Then you can attach the two pieces to some cardboard if necessary.
 
To use it:
You lay the top edge of the dice row directly below the armor class row. 
Say your THAC0 is an 18, place the 18 on 0 and now when you roll the dice you know exactly what armor class each number hits. 
If you have modifiers just slide the scale to the left or right to adjust it. 
This works great if you're the dm and you have multiple enemies with different THAC0s or a player like me who is really bad at doing math in your head.