# IntMath Newsletter - e Day, funny graphs, risk and matrices

By Murray Bourne, 09 Feb 2011

9 Feb 2011

In this Newsletter:

1. Math tip: Happy "e" Day

2. Funny graphs - from GraphJam

3. Math tip: Multiplying matrices

4. Friday math movie: Hans Rosling's 200 Countries, 200 Years, 4 Minutes

5. Math tip: Determining economic risk - Black Scholes formula

6. Friday math movie: Doodling in math class - binary trees

7. Final thought: Security

Hi everyone. Here's hoping the Year of the Rabbit is a prosperous one for you all - in both learning and living!

(Actually, there is some interesting math associated with rabbits, like Fibonacci's Sequence and differential equations).

On with the Newsletter!

## 1. Happy "*e*" Day

We celebrate "*e*" day this week, on 7th February (since *e* = 2.718281828459...). The number "*e*" is very special in math, in a similar way that "pi" is special.

One of the most amazing equations involving *e* is Euler's Formula:

e= cos^{ix}x+isinx, wherei= √(−1)

This formula makes the connection between the exponential function, trigonometry and the imaginary unit. (See Polar form of a Complex Number.)

In the special case when *x* = π, we get

e^{iπ}+ 1 = 0

This profound formula connects the numbers *e*, *i*, π, 1 and 0, with the fundamental operations plus (+) and equals (=).

You can read more about "*e*" here: Exponential and Logarithmic Functions.

## 2. Funny graphs - from GraphJam

**Suitable for: **Everyone.

This is fun - our lives in graphs. |

## 3. Multiplying matrices

**Suitable for: **Everyone. Even if you haven't studied matrices yet, this will give you a good overview of what they are and how to multiply them.

This article points to 2 intereactives that show how to multiply matrices. |

## 4. Friday math movie: Hans Rosling's 200 Countries, 200 Years, 4 Minutes

**Suitable for: **Everyone.

Here's a fascinating animation of wealth trends over the last 200 years. Friday math movie: Hans Rosling's 200 Countries, 200 Years, 4 Minutes |

## 5. Determining economic risk - Black Scholes formula

**Suitable for: **Those who want to see an important application of math. There are many strands of math in this article (logarithms, calculus, statistics, probability).

The Black Scholes Model is one of the many formulas used by the mathematical financial wizards to price options. How does it work? |

## 6. Friday math movie: Doodling in math class - binary trees

**Suitable for: **Everyone.

Bored in your math class? Here's some doodles that may make it more interesting, from Di Hart. |

## 7. Final thought – security

This quote comes from the highly successful industrialist, Henry Ford. He made a vast fortune from mass-producing motor vehicles.

If money is your hope for independence you will never have it. The only real security that a man will have in this world is a reserve of knowledge, experience, and ability.

Henry Ford

Until next time, enjoy whatever you learn.

See the 4 Comments below.