Clara Armstrong, RN, NP
Clara Armstrong, RN, NP is an Adult Health Nurse Practitioner in Chicago, IL, registered under NPI 1558330696.
Getting there
The practice address on file is 820 S DAMEN AVE, Chicago, IL 60612. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 209002939 | IL | Adult Health Nurse Practitioner primary |
This provider holds licence 209002939 issued in IL. 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 Adult Health covers
Definition to come... NUCC Health Care Provider Taxonomy, code 363LA2200X
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 | 1558330696 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Mar 14, 2006 |
| Last updated | Jul 13, 2026 |
| Status | Active |
| Sole proprietor | No |
| Gender | Female |
| Credential | RN, NP |
| Practice address |
820 S DAMEN AVE Chicago, IL 60612 (312) 569-8387 Fax (312) 569-6110 |
| Mailing address |
49 E 90TH ST Chicago, IL 60619 |
| Other names |
Clara Armstrong-edwards Other Name |
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 | 5 | 5 | 8 | 3 | 3 | 0 | 6 | 9 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 5 | 1 | 8 | 6 | 3 | 0 | 6 | 9 |
Sum = 64 · next multiple of 10 = 70 · 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.