I'm going to give you the benefit of the doubt and assume you misread the post you are replying to, which referred to the last 4 digits of a SSN, and incorrectl

I'm going to give you the benefit of the doubt and assume you misread the post you are replying to, which referred to the last 4 digits of a SSN, and incorrectly assumed we were talking about full SSNs. Because otherwise your statement is absurdly wrong. If there are 10,000 possible 4 digit combinations and 8,000 people in a ZIP code on average, the odds that someone else will share the last 4 digits of my SSN is 1-(1-1/10000)^7999 which comes out to 55%. So in reality, more often than not, you will share the last 4 digits of your SSN with someone in your zip code. Also, there are a few zip codes with 100,000+ people in them, and many zip codes with 50,000+ people in them. These zip codes account for many millions of people. You are guaranteed that nearly every resident will share the last 4 digits of their social security number with at least one other person in these zip codes.