Problem of the Month

September 2008

Diophantus was a famous Greek mathematician who lived and worked in Alexandria, Egypt sometime around the third century.  After he died, someone described his life in this puzzle:

He was a boy 1/6 of his life.

After 1/12 more, he acquired a beard.

After another 1/7, he married.

In the fifth year of his marriage, his son was born.

The son lived half as many years as his father.

Diophantus died 4 years after his son. 

How old was Diophantus when he died?

The answer will be revealed along with a new problem next month.

Problem of the Month

February 2007

Suppose you have an unlimited supply of 5-cent and 11-cent stamps.  You can make exact postage of 21 cents with two 5-cent stamps and one 11-cent stamp.  However, you cannot make postage of 23 cents by using only 5-cent and 11-cent stamps.  What is the greatest amount of exact postage that you cannot make?  Be able to prove your answer.

The answer will be revealed along with a new problem next month.

January Answer: The Smedleys were on vacation for 18 days.  There were 7 cloudy mornings which were followed by clear afternoons.  There were 6 cloudy afternoons which were preceded by clear mornings.  Finally, there were 5 days that were clear all day.