The 17-digit VIN number of every car manufactured in, or imported to, the U.S. since 1981 has a check digit in its 9th position. The value of the check digit depends upon the characters in the remaining 16 locations. It is computed by the following algorithm:

Each of the characters in the VIN is assigned a value. If the character is a digit 0-9, it is assigned that value. If the character is alphabetic, it is assigned a value as follows:

• .A=1, B=2, C=3, D=4, E=5, F=6, G=7, H=8, I=9,
• .J=1, K=2, L=3, M=4, N=5, O=6, P=7, Q=8, R=9,
• .S=2, T=3, U=4, V=5, W=6, X=7, Y=8, Z=9.

Note that the sequence S,T,U,.. begins with 2,3,4,.. and not 1,2,3,...

Each of the positions in the VIN is assigned a weight taken sequentially from the following list:

• .{8, 7, 6, 5, 4, 3, 2, 10, -, 9, 8, 7, 6, 5, 4, 3, 2}.

That is, position 1 has a weight of 8, position 2 has a weight of 7, and so forth. The 9th position is the location of the check digit and does not enter into the computation.

The check digit is computed by multiplying the value of each character by its positional weight, summing the products, and dividing the sum by 11. The remainder is the value of the check digit; if the remainder is 10, the check digit is assigned the character 'X'.

As an example, consider the VIN

• .WBAAF931XMEE68337

Translating the characters into values gives the result

• .62116931-45568337

The values, when multiplied by the positional weights, give the sequence

• .{48, 14, 6, 5, 24, 27, 6, 10, -, 36, 40, 35, 36, 40, 12, 9, 14}
  
  whose sum is 362. Division by 11 leaves a remainder of 10, so the check digit is an 'X', as indicated.