The Check Digit is a function of all other digits in the IMEI. The purpose of the Check Digit is to help guard against the possibility of incorrect entries to the CEIR and EIR equipment.
The check digit is validated in three steps:
1. Starting from the right,
double a digit every
two digits (e.g., 5 → 10)
double a digit every
two digits (e.g., 5 → 10)
2. Sum the digits (e.g., 10 → 1+0).
Check if the sum is divisible by 10.
Check if the sum is divisible by 10.
3. Conversely, one can calculate
the IMEI by choosing the check
digit that would give a sum
divisible by 10.
the IMEI by choosing the check
digit that would give a sum
divisible by 10.
IMEI: 35145120840121
1. (5x2, 4x2, 1x2, 0x2, 4x2, 1x2, 1x2) = (10, 8, 2, 0, 8, 2, 2)
2. (1+0+8+2+0+8+2+2) + (3+1+5+2+8+0+2 ) = 44
3. Luhn Digit : 6
IMEI: 351451-20-840121-6
More info...
1. (5x2, 4x2, 1x2, 0x2, 4x2, 1x2, 1x2) = (10, 8, 2, 0, 8, 2, 2)
2. (1+0+8+2+0+8+2+2) + (3+1+5+2+8+0+2 ) = 44
3. Luhn Digit : 6
IMEI: 351451-20-840121-6
More info...
CHECK IMEI 
