@phillik747
The Tail Number you enter are actually the last three digits of the aircraft’s Bureau Number (BuNo), or the USN/USMC serial number. For tactical aircraft, the BuNo is unrelated to the aircraft’s “Side Number” (the one you see painted on the nose and flaps). The “Side Number” you see on the aircraft is the first the first BuNo digits reversed so that there is no obvious correlation.
In your case: “210” entered in the Tail Number will give “12” on the aircraft’s “Side Number”.