Pi belongs to a huge mathematical group called irrational numbers, which go on forever and cannot be written as fractions. Scientists have calculated pi to 105 trillion digits, although most of us are more familiar with the approximation 3.14. But how do we know that pi is an irrational number?

Pi Day is a favorite holiday for both food lovers and mathematicians. For the foodies, the reasoning is simple. Pi Day brings discounts and deals for people looking to grab a pizza to celebrate the holiday.