Creating formula for Check Digit following ten digit number

[samual]

Hello,

Our exact problem is this: We have a ten digit number, 6134217948, and we need to find a check digit for it. We have a manual formula which invovles multiplying every other number, i.e. 1,4,1,9,8, by two, and then adding the sum of the resulting numbers to the sum of the rest, i.e. 6,3,2,7,4. However if any of the first string of numbers multiplied by two is larger than 9, than it drops the tenths digit and has a one added to it.

For example 1 4 1 9 8 individually multiplied by 2 equals 2 8 2 18 16, which is changed to 2 8 2 9 7.

After this is said and done the two strings are added back together, ie (2+4+2+9+7)+(6+3+2+7+4) and the ones column of the resulting number is subtracted from ten to equal our check digit number.

While we can manage all of this manually, we need help making a formula to mass produce this in excel.

Any help would be very welcome,

Thank You.

 

[Joe Was]

The only way I know of is with VBA macro code.

 

[Jonmo1]

Is this what you're looking for...

=10 - RIGHT(SUM(MOD(MID($A2,2,1)*2,10)+(--MID($A2,2,1)*2>9),MOD(MID($A2,4,1)*2,10)+(--MID($A2,4,1)*2>9),MOD(MID($A2,6,1)*2,10)+(--MID($A2,6,1)*2>9),MOD(MID($A2,8,1)*2,10)+(--MID($A2,8,1)*2>9),MOD(MID($A2,10,1)*2,10)+(--MID($A2,10,1)*2>9),--MID($A2,1,1),--MID($A2,3,1),--MID($A2,5,1),--MID($A2,7,1),--MID($A2,9,1)),1)

 

[pcorpz]

put the upc on cell c4, then on cell d4 put this formula

=ROUNDUP((MID(C4,1,1)+MID(C4,3,1)+MID(C4,5,1)+MID(C4,7,1)+MID(C4,9,1)+MID(C4,11,1))*3+(MID(C4,2,1)+MID(C4,4,1)+MID(C4,6,1)+MID(C4,8,1)+MID(C4,10,1)),-1)-((MID(C4,1,1)+MID(C4,3,1)+MID(C4,5,1)+MID(C4,7,1)+MID(C4,9,1)+MID(C4,11,1))*3+(MID(C4,2,1)+MID(C4,4,1)+MID(C4,6,1)+MID(C4,8,1)+MID(C4,10,1)))

this will give you the check digit.

then on column e, you can put this formula to combine the two

=CONCATENATE(C4,D4)

 

[facethegod]

Enter a 10 digit nuber in a1 and try this in b1 to get your check digit

Here's my shot confirmed with Ctrl + Shift + Enter

=10-(RIGHT(SUM(IF(MID(A1,{2,4,6,8,10},1)*2>9,MOD(MID(A1,{2,4,6,8,10},1)*2,10)+1,MID(A1,{2,4,6,8,10},1)*2))+SUM(MID(A1,{1,3,5,7,9},1)+0),1)+0)

 

[samual]

Thanks

Thank you so much! This helped a lot.

 

[Richard Schollar]

Hi Samuel

PGC01 shows how to create a Luhn check digit formula for numbers that aren't limited to only 10 digits (ie 12,15, 18 etc are possible):

http://www.mrexcel.com/board2/viewtopic.php?p=1305201#1305201