Digit : A digit is a symbol used in the representation of a number.

Number : A number $x$ is a mathematical symbol representing a quantity.

Ones digit : The first digit left of the decimal point (or the digit furthest to the right if there is no decimal point). It counts multiples of 1.

Centimeter : A centimeter ($cm$) is $\frac{1}{100}$ of a meter.

Equilateral : A polygon that has side lengths that are all equal is called equilateral polygon.

Length : Length is the attribute of a one-dimensional shape that can be measured with a measuring tape.

Perimeter : The perimeter of a two-dimensional shape is the length of the boundary of the shape. For a polygon this is the same as the sum of all the side lengths. For example a triangle with side lengths 1, 2 and 3cm has a perimeter of 1+2+3=6cm. The perimeter of a circle is referred to as its circumference.

Quadrilateral : A quadrilateral or quadrangle is a polygon with four corners. Rectangles, trapezoids, kites, rhombuses, squares and parallelograms are all specific kinds of quadrilaterals. The sum of the interior angles in a quadrilateral is always $360^{\circ}.$

Sum : A sum is the result of an addition.

Centimeter : A centimeter ($cm$) is $\frac{1}{100}$ of a meter.

Cube : A cube is a three-dimensional shape with 6 faces that are all squares. A cube has 8 corners and 12 edges.

Cubed : The cube of a number $x$, or $x$ cubed or $x^3$ is the third power of $x$: $x^3=x\cdot x\cdot x.$ For example 2 cubed equals 8.

Diameter : The diameter of a circle is the length of a line segment from the boundary of a circle through the center of the circle to the boundary on the other side of the circle.

Half : A Half is the number equal to $\frac{1}{2}=0.5.$

Number : A number $x$ is a mathematical symbol representing a quantity.

Pi : Pi or $\pi$ is an irrational number approximately equal to 3.14 that is defined as the quotient of the circumference and the diameter of a circle.

Quarter : One quarter is the number $\frac{1}{4}=0.25.$

Ratio : A ratio is a comparison of two numbers using a division.

Sphere : A sphere is a three-dimensional shape that has a boundary equal to a set of points with a constant distance to a point. The point is called the center of the sphere and the distance is called the radius $r$ of the sphere. The volume of a sphere with radius $r$ is $\frac{4}{3}\pi r^3$ and the surface area is $4\pi r^2.$

Volume : Volume refers to the size of a three-dimensional objects measured by how many unit cubes it would take to fill the shape.