Grade school math students are likely familiar with teachers admonishing them not to just guess the answer to a problem. But a new proof establishes that, in fact, the right kind of guessing is ...

Melting and freezing are both physical changes, which are often easy to reverse. To reverse this process, the water would need to be cooled enough until it freezes back into ice. This works because ...

Mr and Mrs Wallace hire a van for moving house. They see this advert in the local paper and decide to use this company. When they hand the van back, their bill comes to £59. How many hours did they ...

Most linear algebra courses start by considering how to solve a system of linear equations. \[ \begin{align} a_{0,0}x_0 + a_{0,1}x_0 + \cdots a_{0,n-1}x_0 & = b_0 ...