Illinois is in the Central Time Zone in the United States of America (USA). US Central Standard Time (CST) is 6 hours behind Greenwich Mean Time (GMT-6).
Credit Card Account Number Verification - Card Type Identification. This page provides information about identifying a credit card type from a card number's numeric range and number of digits. First digit must be a 3 and second digit must be a 4 or 7. Valid length: 15 digits. First digit must be 3 and second digit must be 0, 6, or 8. Valid length: 14 digits. Valid length: 16 digits.
To try and minimize this, credit card numbers contain a check digit. In a typical sixteen digit credit card number, the first fifteen digits are determined by the issuing bank, but the last digit, called the check digit, is mathematically determined based on all the other digits.