A resident's sliding scale insulin order is as follows:
- 151-200 mg/dL: 2 units
- 201-250 mg/dL: 4 units
- 251-300 mg/dL: 6 units
- >300 mg/dL: Call Nurse
The QMA checks the resident's blood glucose before lunch, and the reading is 248 mg/dL.
How many units of rapid-acting insulin should the QMA prepare to administer?