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谁能帮助阐述一下手机IMEI的check digit(CD)的计算方法
有英文的但是没有看懂
Computation of CD from the IMEI proceeds as follows:
Step 1: Double the values of the odd labelled digits D1, D3, D5 ... D13 of the IMEI.
Step 2: Add together the individual digits of all the seven numbers obtained in Step 1, and then add this sum to
the sum of all the even labelled digits D2, D4, D6 ... D14 of the IMEI.
Step 3: If the number obtained in Step 2 ends in 0, then set CD to be 0. If the number obtained in Step 2 does not
end in 0, then set CD to be that number subtracted from the next higher number which does end in 0.
Example of computation
IMEI (14 most significant digits):
TAC FAC SNR
D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1
2 6 0 5 3 1 7 9 3 1 1 3 8 3
Step 1:
2 6 0 5 3 1 7 9 3 1 1 3 8 3
x2 x2 x2 x2 x2 x2 x2
12 10 2 18 2 6 6
Step 2:
2 + 1 + 2 + 0 + 1 + 0 + 3 + 2 + 7 + 1 + 8 + 3 + 2 + 1 + 6 + 8 + 6 = 53
Step 3:
CD = 60 - 53 = 7
例子里面的step 2是怎么得来的? |
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