### Topic Pages

##### Ramsey, Frank Plumpton (1903 - 1930)

British philosopher and mathematician, best known for his work on the foundations of mathematics, but also made remarkable contributions to

##### Range

The range of a distribution of values is the difference between the highest and lowest values of a variable or score. In other words, it is a single

##### ratio

Measure of the relative size of two quantities or of two measurements (in similar units), expressed as a proportion . For example, the ratio of vowels

##### Real numbers

A number that can be written in the form ±n:a1a2a3 …, where n is an integer and each a i is one of the digits 0 to 9, for example, 2, ⅓ = 0:333 …,

##### Rectangles

Quadrilateral (four-sided plane figure) with opposite sides equal and parallel and with each interior angle a right angle (90°). Its area A is the

##### Riemann, Bernhard, 1826-1866

Place : Germany Subject : biography, maths and statistics German mathematician whose work in geometry - both in combining the results of others and in

##### Right triangle

Triangle in which one of the angles is a right angle (90°). It is the basic form of triangle for defining trigonometrical ratios (for example, sine,

##### Rittenhouse, David (1732 - 1796)

American instrument maker, inventor, and astronomer. He is credited with being the first to introduce the use of cross hairs (spider web) in transit

##### Roman numerals

Ancient European number system using symbols different from Arabic numerals (the ordinary numbers 1, 2, 3, 4, 5, and so on). The seven key symbols in

##### Russell, Bertrand (1872 - 1970)

1872–1970, British philosopher, mathematician, and social reformer, b. Trelleck, Wales. The Early Years Russell had a distinguished background: His