ISBN-10 identifiers are ten digits long.

Those are 4 digits.

1293 is false? shouldnt isnt 1 * 1 + 2 * 2 + 9 * 3 + 3 * 4 = 44? 44 % 11 is 0

I am unable to view the comment because it is flagged as a spoiler 😕

If you want easier kata you can sort the the 8kyus. They are normally sorted by newest. You can sort them by easiest or most completed to get easier katas

No, copy your code, click reset, paste it and try again.

Did anyone else get this error:

src/test/java/Test.java:2: error: Test is already defined in this compilation unit
import org.junit.Test;
^
1 error

Please use spoiler flag next time.

what did you suggest ?

The description may be a bit difficult to understand for some, but your "improvement" would be plain wrong.

fixed

Java version sample tests err with my code, but full test suite passes. Java 8 shows two issues, Java 11 + - 1 issue (still, the sample test, did not work for me).

yeah, this should probably be 7 kyu, I dont think it is hard enough to be 6, but definitely 7