R
Range:	The difference between the smallest and largst data items.
Ray	A line with a starting point but no endpoint.
Real Numbers	All rational and irrational numbers.
Rectange	A quadrilateral with four right angle and two pairs of opposite parallel sides.
Recurring or Repeating Decimals	A repeating patterns of digits.
Reflection	A mirror view
Reflex Angle	Any angle between 180 and 360 degrees.
Regular Shapes	Shapes where all the sides and angles are equal.
Revolution	A comlete 360 degree turn.
Rhombus	parallelogram with four equal sides and equal opposite angles.
Right Angle	An angle measuring 90 degrees.
Rotation	To turn an object.
Round	To change a number to a more convenient value.
Row	Items arranged in a horizontal line.