Originally Posted by Tech Explorer
When I pay at the supermarket, the machine asks me what card it is.
I recall that MC starts off with a 5, Visa cards with a 4, AMEX with a 3 and Discover cards with a 6. I'm speculating that the number of digits and the starting numbers are factors in how the transaction gets processed.
The leading digit is in fact the card company identifier. MC, VISA, and Discover use 4 groups of 4 on the card face. Am EX is the oddball of the lot with only 15 digits in a unique arrangement.
However on the mag stripe the arrangement is different. How many numbers in each cluster and the numbers themselves are how the card is identified to the bank you have it issued from or a POS vendor.
If the machine you swipe your card through is asking what type, as in MC and the rest, could mean the card is damaged or worn out. It could also mean the credit card machine's software is out of date. Or the reader head needs cleaned. Dirty heads have trouble reading cards swiped through it.
But if the machine is asking how you want charged, either credit or debit, is a courtesy. Because there are different rates and fees on debit versus credit, It's not uncommon to have a CC machine how you want your card nuked. And it stems from charge backs being filed by the card holder, because the card was not charged in the correct manner.
I have 30 years in the hotel biz. People have no idea how big of a pita it can be sometimes with plastic money.