write a program that asks the user for a 9-digit integer, computes its checksum, and then prints the corresponding ISBN number.

 

The International Standard Book Number (ISBN) is a 10-digit code that uniquely specifies a book. The rightmost digit is a checksum digit that can be uniquely determined from the other 9 digits, from the condition that d1 + 2d2 +3d3 + ... + 10d10 must be a multiple of 11 (here di denotes the ith digit from the right).

 

The checksum digit d1 can be any value from 0 to 10. The ISBN convention is to use the character X to denote 10.

 

The checksum digit corresponding to 032149805 is 4 since 4 is the only value of x between 0 and 10 (both inclusive), for which 10·0 + 9·3 + 8·2 + 7·1 + 6·4 + 5·9 +4·8 +3·0 + 2·5 + 1·x is a multiple of 11.

 

Sample runs would be as follows.

 

• Sample run 1:

Please enter a nine digit integer: 013376940

The corresponding ISBN number would be 0133769402.

 

• Sample run 2:

Please enter a nine digit integer: 013376947

The corresponding ISBN number would be 013376947X