Know your no.
One thing that seems to surprise many people is that Americans memorize the last four digits of their social security number. A lot of countries have this sort of numbering system for their citizens, whether it’s a national insurance number, a citizen card, or even a My Number like in Japan.
Basically, our Social Security Number is used for almost every aspect of our lives. Our local governments keep track of our earnings, location, credit, and all sorts of things by our SSN. Also, if you lose your bank card, you’ll have to recite the last four digits to verify that you’re the account holder.