I have been learning how to use the API's in my spare time, and I have a question regarding the notation I found at www.vbapi.com. For the GetLogicalDrives api, the example is given as

If (driveflags And 1) = 1 Then Debug.Print "Drive A: exists."
If (driveflags And 2) = 2 Then Debug.Print "Drive B: exists."
If (driveflags And 4) = 4 Then Debug.Print "Drive C: exists."
If (driveflags And 8) = 8 Then Debug.Print "Drive D: exists."

My question is, where do the numbers (1,2,4,8 etc) come from? Are there specific numbers assigned to each potential drive letter? How do you find out what the others are? Thanks for the help.

Mark