Something that my friend mentioned sparked this question. He said that he saw some program somewhere where some identity thieves were able to discern the entire credit card number by just knowing the last 4 digits. I was skeptical of his claim because it would be almost a total crapshoot trying to guess one of the trillion combinations for the first twelve digits (not to mention the expiration date and the 3 digit security code on the back). Yeah IIRC each bank has a unique combination for the first 4 digits, but after that I will plead total ignorance.
So am I risking ID theft if I don’t burn/shred any receipt containing the last 4 digits, or is this something I really shouldn’t worry about?