General

The Verhoeff algorithm is a checksum formula for error detection developed by the Dutch mathematician Jacobus Verhoeff and was first published in 1969.

• Wikipedia Source
• Algorithm Implementations

Validator

Apache Commons provides the class VerhoeffCheckDigit.

Calculate a checksum

@Test
public void calculateChecksum()throws CheckDigitException{
    // given
    String companyCode="90368002";
    String expectedChecksum="3";

    // when
    String actual=VerhoeffCheckDigit.VERHOEFF_CHECK_DIGIT.calculate(companyCode);
    logger.info("Checksum for {} is {}",companyCode,actual);
    //then
    assertEquals(expectedChecksum,actual);
}

Validate a code

@Test
public void validateChecksum(){
    // given
    String code="903680023";
    String faultyCode="1256369654";
    // when && then
    assertTrue(VerhoeffCheckDigit.VERHOEFF_CHECK_DIGIT.isValid(code));
    assertFalse(VerhoeffCheckDigit.VERHOEFF_CHECK_DIGIT.isValid(faultyCode));
}