MOD SEVEN CALCULATION
The mod-seven formula is a way of generating a check-digit number. There are many things in CARS+ that use this logic. Among them:
PC numbers (Hertz only)
Some RA numbers (Hertz and Dollar)
Some Vehicle numbers (Dollar)
Some Frequent Traveler numbers
The formula involves treating the significant digits as a single number; then divide that number by 7. The remainder is the check digit. The logic for calculating the check digit when appropriate resides within CARS+. The explanation of the formula given below is for informational purposes.
Example 1:
RA # 12345678.
The formula is: 12345678 divided by 7 = 1763668.286
To obtain the check digit, take the decimal portion which is carried out to the 3rd place (.286) and multiply by 7. Which is .286 x 7 = 2.00
Round off to the nearest whole number (2). This is the check digit.
The RA number with the check digit is then: 12345678-2 (hyphen is not typed when accessing the RA)
RA # SC001564
Formula: 1564 divided by 7 = 223.429
.429 x 7 = 3.00
Check digit is 3; RA with check digit is SC001564-3
Example 3:
Vehicle # FD0015
Formula: 15 divided by 7 = 2.143
.143 multiplied by 7 = 1.00
check digit = 1
Vehicle number with check digit = FD0015-1 (hyphen is not typed when accessing the vehicle)
Example 4:
PC # AM7
Formula: 7 divided by 7 = 1.00
Check digit is zero
Result: AM7-0 (hyphen is not typed when entering the PC number)