## Monday, February 4, 2013

### Celebrate e Day in the Math Classroom

Although it's not as well known as Pi, e is also an irrational number that occurs naturally in mathematics. With a numerical equivalent of approximately 2.71828183,  e is used in helping to decipher exponential and logarithmic functions. It's simple mathematical expansion is infinite. Rounding e to the nearest tenth we get 2.7, so e Day is celebrated on 2-7 each year.

On February 7, you can introduce your students to e Day with a classroom celebration. Sample foods that start with e (eggplant dip, escarole wraps, candy eggs, edame, or anything edible), read the poetry of ee cummings, solve some easy mathematics equations, do an Excel Math lesson, try some e-learning apps or computer technology (such as our Timed Basic Fact Practice), or do some fun math related to e.

In Excel Math, students build a strong foundation in math so they are prepared for higher learning. Students work with a variety of mathematical concepts each day. They tackle word problems, brain teasers, and cooperative learning. They learn to evaluate and solve problems, rather than perform algorithms by rote. Learn more on our website: www.excelmath.com/tour/tour01.html.

The music, "The Sound of e" by Carlton Shepherd is based on the irrational number e and includes a video slideshow. The composition was generated programatically via an algorithm over the mathematical constant e. You may want to share a portion of this video with your class:

"The Sound of e" musical composition by Carlton Shepherd

The constant e is also called "Euler's number" because it was first studied by the Swiss mathematician Leonhard Euler. Jacob Bernoulli discovered this constant by studying a question about compound interest: Bernoulli noticed that compounding weekly (n = 52) yields \$2.692597..., while compounding daily (n = 365) yields \$2.714567..., just two cents more. The limit as n grows large is the number that came to be known as e. With continuous compounding, the account value will reach \$2.7182818.... More generally, an account that starts at \$1 and offers an annual interest rate of R will, after t years, yield eRt dollars with continuous compounding. Read more about compounding interest, Euler's number, and Bernoulli at http://en.wikipedia.org/wiki/E_(mathematical_constant).

My college statistics professor at Randolph-Macon Woman's College, Dr. M. Gweneth Humphries (1911-2006) once found an error in her bank statement showing that the bank had not compounded the interest on her account daily, as they had advertised. Although the math was beyond the scope of the first teller she spoke with, Dr. Humphreys was eventually able to prove her point that the bank owed her accrued interest. (I was duly impressed.) Although you may not be interested in calculating your compounded interest without the help of a calculator, it certainly doesn't hurt to be able to do the math. Read more about Dr. Humphreys, the impact she had on her students, and the award given in her name by the Association for Women in Mathematics at http://www.randolphcollege.edu/x17430.xml.

Do you have a mathematics professor who has made an impact on your life? Leave a brief comment below describing how he or she influenced you. Then send a note of thanks via email or snail mail.

How are you celebrating e Day in your classroom? Will you be celebrating Digital Learning Day on February 6 as well?

Excel Math lessons help students develop a love for math as they build confidence, master mathematical concepts, and build a life-long foundation for using (and enjoying) math in everyday life.

New to Excel Math? Learn more by visiting our website: www.excelmath.com or give us a call at 1-866-866-7026. When you call between 8:30 a.m. and 4:00 p.m. Monday - Friday (West Coast time), a helpful person will answer the phone (never a machine).