How To Calculate The Circumference Of A Circle
Mathematics / Geometry
A circle is what you get if you take a straight line and bend it around so that its ends touch. You can demonstrate this by taking a piece of stiff wire and doing just that: bring the ends of the wire continue reading this fact

Unit Of Luminous Intensity (candela)
Mathematics / History
Originally, each country had its own, and rather poorly reproducible, unit of luminous intensity; it was necessary to wait until 1909 to see a beginning of unification on the international level, when continue reading this fact

Perfect Numbers
Mathematics / Number Theory
Some numbers are more special than others. According to Pythagoras (569 BC  475 BC) and Euclid (325 BC  265 BC), some are so special that they called them mystical or perfect numbers. The first per continue reading this fact
