11 entries

Maths words beginning with R

Radius: The distance from the centre of a circle to any point on its edge. It is half the diameter.
Range: In statistics, the difference between the largest and smallest values. For a function, the set of all possible outputs.
Ratio: A comparison of two or more quantities showing how much of one there is relative to another, written with a colon.
Reciprocal: A fraction turned upside down. Multiplying a number by its reciprocal gives $1$ .
Reflex angle: An angle that is more than $180^\circ$ and less than $360^\circ$ .
Regular polygon: A polygon with all sides equal and all angles equal.
Remainder: The amount left over when a number does not divide exactly. It is always smaller than the divisor.
Right angle: An angle of exactly $90^\circ$ , a quarter turn. Often marked with a small square.
Rotational symmetry: A shape has this if it looks the same after being turned by less than a full turn about its centre.
Round: To swap a number for a nearby one that is easier to use, such as the nearest ten or hundred. A digit of $5$ or more rounds up.
Rounding: Replacing a number with a simpler approximate value to a given degree of accuracy, such as the nearest ten or two decimal places.