False assumptions Memes

The mathematical blasphemy here is enough to make any number theorist choke on their cereal. Our confident friend starts eating, thinking 91 is obviously a prime number (it's not even checking if it's divisible by anything?). Then the horrifying truth appears: 91 = 7×13. That moment when your mathematical intuition fails you spectacularly and you realize you've been living a lie. Twenty years of teaching and I still see students confidently declaring numbers prime without bothering to check divisibility rules. The audacity!