1. Pi is one of the most useful and most used numbers around. Most commonly, you’ll see it used in area and volume calculations, but did you know it’s also used in many professions? NASA uses pi when going to space, doctors use it in medical procedures, and even musicians use pi when studying music theory. Whether for volumes, space travel, or music, if you ever need to remember the value of pi, just think about this cool fact – it’s the word PIE, mirrored: 3.14.

2. Speaking of pi (and food), if you need to remember the equation for a cylinder, just think about pizza (and let’s say it’s deep dish so it has some height). If we say our pizza has a radius *z* and height *a*, that means the volume of our pizza is *pizza*! Or rather, *pi * z * z * a*. Pretty nifty, huh?

3. Have you ever been in class with someone and instantly bonded over having the same birthday? Or do you enjoy researching famous people who share your birthday? As it turns out, finding someone with the same birthday is fairly common. In a group of 23 people, there is a 50% chance that two people will have the same birthday! If you love advanced statistics, you can find the math behind the Birthday Problem here, although I’ll warn it is complex and not necessarily pretty. If those formulas look daunting, you can check out a TED video explanation here.

4. If you want to do something no one has ever done before, just shuffle a deck of cards. There are **80,658,175,170,943,878,571,660,636,856,403,766,975,289,505,440,883,277,824,000,000,000,000** different ways to arrange a deck of cards, so chances are the cards have never been shuffled in that exact order before.

5. Next time you’re playing a game with dice, take a look at the dots on each side and you’ll notice that all of the opposite sides add up to seven. If you don’t believe it, you can verify that 1 is opposite 6, 2 is opposite 5, and 3 is opposite 4, all of which add up to 7.

6. Even if you’re a math whiz, it can be easy to make a mistake. Maybe you forgot a decimal, maybe your writing was messy and you ended up switching some numbers around, or maybe you just forgot a basic mathematical principle. But whatever you do, just make sure you’re not dividing by zero. In 1997 when a crewmember on a US Navy warship accidentally entered a zero into the computer, the computer tried to divide by zero, and all of the machines aboard stopped working. This seemingly small mistake led to the ship and crew being stranded for two hours.

7. Take a minute and think about your favorite number…. Got it? Now if you chose 7, you’re not alone. 7 is the most popular favorite number, according to an Internet poll by Alex Bellos, author of a book about how our lives and numbers are intertwined. It’s not exactly clear why 7 is such a popular number; it could be because of how often we see it in our lives (the 7 days of the week), in popular culture (the 7 dwarves), our natural observations (the 7 colors of the rainbow), or maybe because there are 7 reasons on this list. No matter the reason, it’s clear people love 7.