Example: The following formula illustrates the situation:

IF (QUANTITY GE 1, Length*100, Width/50)

Variables are: Length = 25 and Width = 50  

1. In the original pass, the Quantity variable is 1. The formula uses Length*100 to calculate the takeoff quantity (25*100=2500).
2. The Replace Pass operation involves reversing the original pass and adding the replacement pass.
3. In the reverse pass, the Quantity variable is -1. The formula uses Width/50 to calculate the takeoff quantity (2500 – 50/50 = 2499).
4. In the replacement pass, the Quantity variable is 1 again. The formula uses Length*100 to calculate the takeoff quantity (2499 + 25*100 = 4999).