Mary Ann Duffy
Mary Ann Duffy is a School Registered Nurse in Brooklyn, NY, registered under NPI 1003181876. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
Here is what surrounds this office in Brooklyn, based on OpenStreetMap data collected Sep 10, 2026. Parking is available about 0.27 mi away. The nearest transit stop is 0.23 mi away, served by Bay Parkway & McDonald Avenue. A pharmacy sits 0.40 mi from the entrance (Rite Aid), which helps if you leave with a prescription. If you arrive early, there is a coffee shop 0.31 mi away.
Getting here and what is nearby
Parking 751 ft ~3 min
Parking 807 ft ~4 min
Transit 50th Street & 20th Avenue 935 ft ~4 min
Transit Bay Parkway & McDonald Avenue 0.22 mi ~5 min
Grocery GSA King Tomato Farm 0.22 mi ~5 min
Transit Bay Parkway & McDonald Avenue 0.23 mi ~5 min
Parking 0.27 mi ~6 min
Grocery ShopRite 0.29 mi ~6 min
Coffee The Little Things 0.31 mi ~7 min
Grocery Goldbergs 0.35 mi ~7 min
5025 18th Avenue
Pharmacy Rite Aid 0.40 mi ~9 min
Restaurant Laghman Express 0.43 mi ~9 min
6201 20th Avenue, 11204
Mo-Th,Sa-Su 11:00-21:00; Fr 11:00-13:00,14:00-21:00
Gas station BP 0.48 mi ~10 min
Distances are straight‑line estimates — walking routes may be longer. Hours and phone numbers can change; call ahead to confirm.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 3751761 | NY | School Registered Nurse primary |
This provider holds licence 3751761 issued in NY. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
This NPI does not appear in the PECOS Medicare enrolment file. Providers who do not bill Medicare — or who bill only through a group's enrolment — will not appear here. It is not a sign of any problem with the registration.
What School covers
Definition to come... NUCC Health Care Provider Taxonomy, code 163WS0200X
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1003181876 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Mar 13, 2012 |
| Last updated | Mar 13, 2012 |
| Status | Active |
| Sole proprietor | Yes |
| Gender | Female |
| Practice address |
5301 20TH AVE Brooklyn, NY 11204 (718) 377-8845 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 0 | 0 | 3 | 1 | 8 | 1 | 8 | 7 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 0 | 0 | 3 | 2 | 8 | 2 | 8 | 5 |
Sum = 54 · next multiple of 10 = 60 · check digit = 6 · actual last digit = 6
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.