There are two factors to consider when deciding how to handle the problem of a work sample: sample size and population characteristics. Sample size is determined by a formula based on the power of the sample or its ability to represent the population with a predictable margin of error.
The resulting complexity makes card type detection code difficult to write, read, and maintain. As an example of this complexity, consider this JavaScript regular expression used to detect Discover card numbers starting with 6011, 622126-622925, 644-649, and 65:
And three is actually travel and entertainment. MasterCard MasterCard will usually begin with 51-55 with 16 digits. Visa Visa credit card numbers will begin with a 4 and have 13 or 16 digits. American Express American Express will usually begin with a 34 or 37 and have 15 digits.Diner's Club Diner's Club will usually begin with a 36 or 55.asterCard MasterCard will usually begin with 51-55 with 16 digits. Visa Visa credit card numbers will begin with a 4 and have 13 or 16 digits. American Express American Express will usually begin with a 34 or 37 and have 15 digits. Diner's Club Diner's Club will usually begin with a 36 or 55.