## Glossary

**acute angle**

An angle that measures less than 90 degrees.

**angle**

A figure made up of two rays that share the same endpoint.

**common denominator**

The same denominator in two or more fractions. For instance, \(\frac{1}{4}\) and \(\frac{5}{4}\) have a common denominator.

**composite number**

A whole number with more than 1 factor pair.

**denominator**

The bottom part of a fraction that tells how many equal parts the whole was partitioned into.

**dividend**

The number being divided. For example, when 37 is divided by 5, we call 37 the dividend.

**equivalent fractions**

Fractions that have the same size and describe the same point on the number line. For example, \(\frac{1}{2}\) and \(\frac{2}{4}\) are equivalent fractions.

**factor pair of a whole number**

A pair of whole numbers that multiply to result in that number. For example, 5 and 4 are a factor pair of 20.

**intersecting lines**

Lines that cross.

**line**

A set of points that are arranged in a straight way and extend infinitely in opposite directions.

**line of symmetry**

A line that divides a figure into two halves that match up exactly when the figure is folded along the line.

**mixed number**

A number expressed as a whole number and a fraction less than 1.

**multiple of a number**

The result of multiplying that number by a whole number. For example, 18 is a multiple of 3, because it is a result of multiplying 3 by 6.

**numerator**

The top part of a fraction that tells how many of the equal parts are being described.

**obtuse angle**

An angle that measures greater than 90 degrees.

**parallel lines**

Lines that never intersect.

**perpendicular lines**

Lines that intersect creating right angles.

**point**

A location along a line or in space.

**prime number**

A whole number that is greater than 1 and has exactly one factor pair: the number itself and 1.

**ray**

A line that ends at one point and goes on in the other direction.

**remainder**

The number left over when we take away as many equal groups as we can from a number.

**right angle**

An angle with a measurement of 90 degrees.

**right triangle**

A triangle with a 90 degree angle.

**rounding**

A formal way to say which number a given number is closer to. For example, for 182, the number 180 is the closest multiple of ten and 200 is the closest multiple of a hundred. We can round 182 to 180 (if rounding to the nearest ten) or 200 (if rounding to the nearest hundred).

**segment or line segment**

A part of a line with two endpoints.

**straight angle**

An angle that measures 180 degrees.

**symmetry**

A figure has symmetry if its parts can match up exactly when the figure is folded or rotated.

**vertex**

The point where the two rays meet.