.5 ka matalab hai half mm 500 microns and 1 mm = 1000 microns 1 micron = .001 mm .001 mm = 1 micron So hm .5 bhi likh sakte h aur .500 bhi kyoki point k bad .5 kitni bhi zero lga le uska koi matlab nhi h agar .005 number se phle zero lgate h to matlab change hoga .