Numbers are your friends. You may not always agree with this, especially if your weight is too great or your bank account is too small. But numbers have been around for centuries and have helped humans keep track of what is going on in their lives. What are the most favorite or most famous numbers? Try these out for size!

The Greek letter pi represents a value of approximately 3.14159, the ratio between the circumference and diameter of a circle.

The most common applications have to do with computations involving circular objects, but you also find π in weather patterns, statistics, and computer computations.

This decimal value continues on forever without repeating or terminating.

*e*, known as Euler’s number, is approximately 2.71828 and is another nonrepeating, nonterminating number. This number is the natural limit for many science and economics applications.10

^{100}is a Googol. You can write out the entire number with a 1 followed by 100 zeros. This number was the inspiration for the search engine Google.0 has nothing to it. The number 0 was not part of most early counting systems, but its addition was monumental. It allowed for the development of the decimal system. The number 0 is the additive identity because you can add it to a value and not have the value change. But 0 is also

*absorbing*because if you multiply 0 times any value, the value becomes 0.1 is the first counting number. It denotes being the best: “We’re number 1.” The number 1 is the multiplicative identity because you can multiply it times any number and not have the value change.

The Greek letter phi represents the golden ratio or golden mean. Even though its decimal value, approximately 1.618, doesn’t seem all that special, in a ratio the value describes perfect proportions. The golden ratio is found in ancient art and architecture as well as occurring naturally.

911 is most recognizable as the number to call for emergencies. It’s used throughout North America to summon police, ambulances and fire trucks. It’s also, unfortunately, the date of the terrorist attacks on the World Trade Center.

7 is the number most commonly designated as people’s favorite. You have seven days per week, the seven deadly sins, seven continents, seven colors of the rainbow, the seven-year itch, and so on. Many people consider 7 to be their lucky number.

73 is Sheldon Cooper’s favorite number (on the TV show

*The**Big Bang Theory*). Why? Because 73 is 21st prime. Reverse the digits to get 37, the 12th prime. 7 x 3 = 21. And, as everyone knows, 73 in binary form is a palindrome: 1001001.10 is most famous because it’s usually the number of items on “top” or “most” lists!