Misplaced Date (MPD) Mint Error Variety
Misplaced Dates can be accidental but most are caused by a mint employee using a date digit punch to test the punch on the die. The digit would be punched in an area where the strike would obscure the letter so it wasn’t seen on the struck coin, but it didn’t always work as planned.
So some coins will show evidence of a MPD, some will show just one digit and some will show all four. MPD’s are often found in the denticles below the date, or near the base of the bust, it depends on the coin series.
Left is a 1854 Large Cent with part of the 4 visible just below the bust. This variety is called a Newcomb-23. It graded MS64 and sold for $300.
1906 Indian Head Cent FS-302, Snow-14 MPD. Date digits in the denticles. Always look for strange digit shapes in the lower bust, hair and deticles. This example sold for $599 and EF45 examples usually sell for $30.