The healthcare provider (HCP) prescribes penicillin G benzathine 1,800,000 units intramuscularly (IM) for a client with a bacterial infection. The prefilled syringe is labeled, "Penicillin G benzathine 1,200,000 units/2 mL." How many mL should the nurse administer to this client? (Enter numerical value only, rounded to the nearest whole number.)