Month: May 2021

What Happened to Ask Dr. Math?

In January and February of this year, the entire Math Forum site, including Ask Dr. Math, was first moved from to, and then made inaccessible to non-members, by its current owner, the National Council of Teachers of Mathematics. We are hoping that at least some of this material (the pages we often link …

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Arithmetic Series, Backward

Here is a recent question about arithmetic sequences and series (specifically, reversing the process to find the number of terms given the sum), that nicely illustrates a common type of interaction with a student: gathering information about both problem and student, then guiding them to use what they know, or giving new information as needed. …

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How Many Paths from A to B?

A popular kind of question in combinatorics is to count the number of paths between two points in a grid (following simple constraints). This can be done by very different methods at different levels. We’ll look at several problems of this type, starting with the simplest.