It’s easy to tell if a given whole number is divisible by 2. Just check whether the last digit is even. There are also simple rules to determine whether a number is ...

The crisp new dollar bill that I have just taken from my wallet bears the serial number 24598176. It’s easy to tell that the number is exactly divisible by 2 but not by 5. Is it divisible by 3? by 4?

This article shows the application of divisibility to some complex problems that are used to form questions in examinations like CAT. We first show a problem and its detailed solution to clarify that ...

Many students learn divisibility rules in school. These can be fun to play with, but they are often a little tame, and they won’t help you much here. Today I’d like to play around with some stranger, ...

The $q$-tangent number $T_{2n + 1}(q)$ is shown to be divisible by $(1 + q)(1 + q^2) \cdots (1 + q^n)$. Related divisibility questions are discussed. Journal ...