It's an extremely common series. Despite being over 50 years old, one is worth $2-3 on average.
About $2.00
$1.25 to $3.00 each depending on condition.
2.00
Huge numbers of 1957, 1957A, and 1957B $1 silver certificates were printed. None of them is rare; in fact even today they sell for $1.25 to $1.75 in average condition.
"S" is part of the serial number, not the series letter. The series letter is next to the date. Only 3 series were printed - 1957, 1957A, and 1957B In any case these are common among collectors and sell for at most $1.50 or so in circulated condition. Nice uncirculated ones make it all the way to $2.00 or $2.50.
How much is a 1957a silver certificate worth?
About $2.00
$1.25 to $3.00 each depending on condition.
Please see the link below. E 647 is a plate number that does not affect the bill's value.
2.00
Huge numbers of 1957, 1957A, and 1957B $1 silver certificates were printed. None of them is rare; in fact even today they sell for $1.25 to $1.75 in average condition.
6 1957A Silver Certificate Dollars with consecutive serial numbers in 'Crisp-Uncirculated' condition are worth $200.00. You could expect to receive about $50 for the set, if they will all grade GEM CU 65 Any more than that would require certification in grade SUP CU 67 or higher.
"S" is part of the serial number, not the series letter. The series letter is next to the date. Only 3 series were printed - 1957, 1957A, and 1957B In any case these are common among collectors and sell for at most $1.50 or so in circulated condition. Nice uncirculated ones make it all the way to $2.00 or $2.50.
To clear things up:US paper bills are printed, not "cast". "Casting" involves pouring molten metal into a mould; that would not work very well if paper and ink were used.1957A is not the date the bill was printed; it's a "series date" indicating that the bill was part of the second set of $1 bills printed starting in 1957. It's the second set because a new Treasury Secretary and US Treasurer had taken office since the start of the 1957 series.There's more information at the question "What is the value of a 1957 A US 1 dollar silver certificate?".
Please check your bills again. There were no 1957-series $5 bills. 1957 $1 bills are extremely common among collectors and are worth maybe $1.25 to $1.75 in average condition.
What you have is a silver certificate. They used to be redeemable for $1.00 in silver bullion, back in the days when the price of silver was controlled. The 1957 series notes were the last issued before dollar bills were issued as Federal Reserve notes, so a lot were hoarded. In circulated condition your bill might be worth $1.50 to $2.00. FWIW, a bill's serial number is almost always meaningless as a factor in the note's value. There are people who collect "interesting" numbers; e.g. 00000005 or 12344321, but the others are usually ignored.
The series is simply the series date, 1957. Within that, there are 3 subseries, indicated by the possible presence of a letter next to the date. The first set for a given series date is always "plain"; i.e. no letter. After that the letters A, B, C, etc. are used. The letter appears to the right of or below the date, in the same size typeface. The criteria for choosing series dates and letters have changed over the years. At the time 1957 $1 bills were printed, the letter was incremented each time a new Secretary of the Treasury or US Treasurer was appointed. The 1957 series overlapped 2 individuals in each post, resulting in 3 varieties: plain, 1957A, and 1957B.