What is the value of an 1842 US half dollar?

Answer 1

There are multiple varieties of 1842 Liberty Seated half dollar, with different size dates on the front and/or lettering on the back. Look on the back below the eagle to see if there's an "O" mint mark. Numismedia lists the following retail values as of 12/2009:

No mint mark, regardless of the size of the date:
Very worn condition - $29
Moderately worn - $61
Slightly worn - $90
Almost no wear - $350
Uncirculated - $700-14,000 depending on how well-struck it is.

"O" mint mark, large lettering on the back:
Very worn condition - $29
Moderately worn - $58
Slightly worn - $86
Almost no wear - $500
Uncirculated - $1,080-16,000

"O" mint mark, small lettering on the back:
Very worn condition - $720
Moderately worn - $1530
Slightly worn - $2200
Almost no wear - $15,000
Uncirculated - $22,000-47,000

Needless to say, a suspected small-letter 1842-O coin should be authenticated by an expert.