Half of the syringe will be 100mg. The whole syringe is 200mg, 1cc, 1ml
You would draw to .4 on the syringe , should be rite below half of a syringe.
Think of it this way , there's 25 mgs per ever .1 mark so 25 x 4 =100
if you wanted 125 mgs you'd draw to .5 on the syringe or exactly half a syringe.