# Magic Number (Infinite Series)

What if you made a series of unit fractions with the odd numbers as their denominator, added the first two together, subtracted the next one, added the next one and so on. And finally multiplied that number by 4? What number would you get?

# Solar System

When I was young I loved to play with planetary data, to explore their patterns, to learn more about astronomy, and to deal with large numbers. Spreadsheets make it much easier to study the solar system and to find relationships between the planets that are fascinating and unexpected. In the process you will not only learn more science, you will gain spreadsheet skills working with data and functions.

# Work Problems

Suppose Tom can paint the entire fence in twelve hours, and Huck takes eight hours. How long would it take the two of them together to paint the fence?

# Napoleon’s Pyramid

When Napoleon conquered Egypt in 1798 he went to the Great Pyramid of Giza. While his men climbed to its peak, he figured out that “There is stone enough to build a wall 3 meters high and 1/3 meter thick around the whole of France.” Was Napoleon right? How and why did he figure this out?

# Mixture Problems

How many gallons of a 70% alcohol solution must be added to 30 gallons of a 10% alcohol solution in order to produce a new mixture, a 20% alcohol solution?