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Provided Code

public class CheckDigit
{
    /** Returns the check digit for num.
     *  Precondition: 1-6 digits; num >= 0 */
    public static int getCheck(int num) { /* not shown */ }
    /** Returns true if numWithCheckDigit is valid (last digit is the correct check digit).
     *  Precondition: 2-7 digits; numWithCheckDigit >= 0 */
    public static boolean isValid(int numWithCheckDigit) { /* to be implemented in part (a) */ }
}

Part A — 4 Points

Write isValid: extract the check digit (last digit of numWithCheckDigit), extract the number (remaining digits), call getCheck on the number, and return whether it equals the extracted check digit.

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Check Answer   Clear

public static boolean isValid(int numWithCheckDigit)
{
    int checkDigit = numWithCheckDigit % 10;
    int num = numWithCheckDigit / 10;
    return getCheck(num) == checkDigit;
}

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