EXAMPLE: 978 0

4.3 Registrant element

The third element of the ISBN identifies a particular publisher or imprint within a

registration group. The length of this element varies in direct relationship to the anticipated

output of the publisher and may comprise up to 7 digits. Publishers with the largest

expected title outputs are assigned the shortest registrant elements and vice versa. 

Potential registrants apply to the ISBN group agency responsible for the management of

the ISBN system within the country, region, or language group where they are based in

order to be assigned registrant elements that are unique to them. Once they have

exhausted the allocation of ISBNs that is linked to their registrant element, they may be

assigned an additional registrant element providing further allocations of ISBNs. 

EXAMPLE: 978 0 11

4.4 Publication element

The fourth element of the ISBN identifies a specific edition of a publication by a specific

publisher. The length of this element varies in direct relationship to the anticipated output

of the publisher concerned and may comprise up to 6 digits. Publishers with the largest

expected title outputs are assigned the longest publication elements and vice versa. To

ensure that the correct length of the ISBN is maintained, blank digits are represented by

leading zeros.

EXAMPLE 978 0 11 000222

4.5 Check digit 

The fifth element of the ISBN is the check digit. This is calculated using a modulus 10

algorithm.

Each of the first 12 digits of the ISBN is alternately multiplied by 1 and 3. The check digit is

equal to 10 minus the remainder resulting from dividing the sum of the weighted products

of the first 12 digits by 10

with one exception. If this calculation results in an apparent

check digit of 10, the check digit is 0.

Use the following steps to calculate the check digit for the ISBN 978 0 11 000222 ?:

Step 1

: Determine the sum of the weighted products for the first 12 digits of the ISBN (see

following table).

Prefix

Registration

Registrant

Publication element

Check

element

group 

element

digit

Sum

element

ISBN

9

7

8

0

1

1

0

0

2

2

2

?

0

Weight

1

3

1

3

1

3

3

1

3

1

3

1

10