How do you read a brick modular ruler?

The numbers on a modular brick ruler represent how many rows or coarses in 16 inches. There are 6 coarses of modular brick in 16 inches so the number 6 on the ruler would properly space the coarsing to hit at 16 inch inervals. Oversize brick would lay out on a 5. Utility brick lay out on 4. Some glazed tile on a 3. Glass block and concrete block on 2.