What this coin looks like (obverse, reverse, mint mark location, special features, etc.): The Philadelphia Mint produced a 1982 Roosevelt Dime without the "P" mint mark on it. The older style did not have a mintmark which was assumed to be minted in Philadelphia. Although the newer style starting in 1980 included the addition of the "P" mint mark. These dimes with the missing "P" mint mark in 1982 are very rare and valuable.
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD