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.

Partial products method : A method for calculating a product of two multi-digit numbers by writing both numbers as a sum of ones, tens, hundreds and so on, then multiplying each pair of terms and finally summing up all the terms. For example $12\cdot 34=(10+2)\cdot(30+4)$ $=10\cdot 30+10\cdot 4+2\cdot 30+2\cdot 4$ $=300+40+60+8=408.$

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

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.

Edge : An edge of a shape is a line segment between two corners of that shape.

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

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 $m^2.$

Surface area : The surface area of a three-dimensional shape is the area of the surface of the three-dimensional shape. For example the surface area of a cube with edge length 1 $cm$ is 6 $cm^2.$