Are you sure John?

1 rev of motor = 5mm = 200 full steps so one full step = .025mm, microstepping by 4 means one microstep = .025/4mm = 0.00625mm or steps/mm = 1/0.00625 = 160 steps/mm

Done your way = 200 x 4 / 5 = 160


And Joe, there is no such thing as a stupid question... the only stupid thing is not knowing when to ask it... (or so I tell my team)