Addition : Addition is the mathematical operation that describes increasing a number by an amount equal to a second number. The mathematical symbol for addition is the plus sign $+.$ The term addition is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

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.

Ten : Ten refers to the number $10.$

Decimal point : The point in a decimal separating the digits representing multiples of wholes from the digits representing fractions of wholes.

Hundredth : Hundredth refers to the number $\frac{1}{100}=0.01=10^{-2}.$

Ten thousand : Ten thousand refers to the number $10,000=10^4.$

Ten thousandth : Ten thousandth refers to the number $\frac{1}{10,000}=0.0001=10^{-4}.$

Area : The amount of unit squares that is needed to cover a 2-dimensional shape.

Base : When using the height of a triangle or parallelogram (for example in an area calculation), base refers to the side of the triangle or parallelogram that the height starts out at. In a logarithm $\log_{b}x$ or power $b^x$ base refers to the number $b.$

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

Height : In a triangle a height (or altitude) is the shortest line segment that connects a side to its opposing corner. A height of a triangle is perpendicular to the side is started at. The three heights of a triangle intersect in a point, the so called orthocenter of the triangle. In a parallelogram the height is the shortest distance between two opposing sides. In a pyramid the height is the shortest distance between the base area and the corner of the pyramid that is not part of the base area. In a prism the height is the shortest distance between the two base faces.

Parallelogram : A parallelogram is a quadrilateral with 2 pairs of parallel sides. Rectangles, rhombuses and squares are special kinds of parallelograms.

Square centimeter : Square centimeter or $cm^2$ is a unit of measurement for measuring area. 1 square centimeter is the area of a square with side length 1 $cm,$ so 10,000 $cm^2$ are one $m^2.$