****NUMBERING OF FREIGHT WAGONS IN INDIAN RAILWAYS****
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For example: 61250619336
Separate all the digits of this number starting left to right and name them as C1, C2, C3, etc. till the last digit....
more...

6 -- C1
1 -- C2
2 -- C3
5 -- C4
0 -- C5
6 -- C6
1 -- C7
9 -- C8
3 -- C9
3 -- C10
6 -- C11
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Part I:-
6 -- C1
1 -- C2
61 -- C1 C2
It indicates the type of wagon (BCNA/BOXN/BOBYN/BOSTHMS/BTPN).
For example: '61' indicates BLCA Wagon.
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Part II:-
2 -- C3
5 -- C4
25 -- C3 C4
It indicates the owning railway of the wagon (Central Railways/Eastern Railways/Defence/Private Parties).
For example: '25' indicates a wagon owned by CONCOR.
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P.S.: For more clarity on the first four digits, kindly go through the next answer on this question.
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Part III:-
0 -- C5
6 -- C6
06 -- C5 C6
It indicates the year of manufacture of the wagon.
For example: '06' indicates a manufacturing year of 2006.
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Part IV:-
1 -- C7
9 -- C8
3 -- C9
3 -- C10
1933 -- C7 C8 C9 C10
It indicates the individual serial number of the wagon.
0001 - 0999 -- Used for departmental freight wagons
1000 - 9999 -- Used for all other freight wagons
For example:-
'1933' indicates a freight wagon used for non-departmental activities.
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Part V:-
6 -- C11
Step 1 : Starting from the left, add all the Characters in the even position. S1 = C2 + C4 + C6 + C8 + C10.
Step 2 : Multiply the sum by 3 to get 3×S1.
Step 3 : Starting from the left, add all the Characters in the odd position. S2 = C1 + C3 + C5 + C7 + C9.
Step 4 : Add the sum of step 2 to the sum of step 3 to get S4= 3×S1+S2.
Step 5 : Round this total up to the next multiple of 10.
Step 6 : The check digit is the number required to the added to round up to the next multiple of 10.
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For example:-
Let the wagon number be 61250619336.
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Step 1:-
1 -- C2
5 -- C4
6 -- C6
9 -- C8
3 -- C10
S1 = 1+5+6+9+3 = 24
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Step 2:-
3XS1 = 3X24 = 72
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Step 3:-
6 -- C1
2 -- C3
0 -- C5
1 -- C7
3 -- C9
S2 = 6+2+0+1+3 = 12
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Step 4:-
S4 = 3XS1 + S2 = 72+12 = 84
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Step 5:-
Next 10th multiple of 84 = 90
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Step 6:-
Check digit = 90-84 = 6
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Hence, the 11th digit assigned to this freight wagon is '6'.