Category: Ratio

Fibonacci’s Sequence

Fibonacci, the nickname given the great medieval mathematician Leonardo of Pisa, is connected in most of our minds with the Fibonacci sequence. Spreadsheets make wonderful tools for creating such sequences. This one is amazingly simple. Just select a cell, any cell and write a formula in that cell that adds together the two cells above it. Now copy that cell down the spreadsheet and seed it with 1 in the first cell. The Fibonacci sequence is a pattern that this action shows very well. This sequence has surprising attributes, and we explore some of them as well.

Triangular Numbers

1, 3, 6, 10… are called the triangular numbers because they can be stacked up to form a triangle. They are very interesting numbers, and they form a very interesting pattern when graphed.

Can you guess the next triangular number? Can you guess the shape of the graph of the triangular numbers? Can you explain that graph?

Prime Numbers

The prime numbers are among the most fascinating objects in all of mathematics. While we can generate them, we do not know or understand their pattern. Yet, they have some fascinating patterns that we can easily see like the twin primes. We found on the Web a Conditional Formatting formula by Bob Umlas that colors prime number cells so you can see their pattern. I find playing with prime patterns great fun.

Interest

Which form of interest, simple or compound, is the fairest? If you were buying a house or a car which would you rather have, which would you consider fair? Or if you had your money in a bank account earning interest, which would you consider the fairest way to calculate that interest? We will show you how to calculate each and help you think about what is fair as far as interest is concerned.

Exploring Triangles

Create, manipulate, and explore triangles in this live interactive spreadsheet. On the surface, a triangle is being drawn on a graph, but the real magic lies in the formulas used to make this spreadsheet work.