To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(8a)(8ab) - (8a²)(3b)
(8 x 8)(a x a x b) - (8 x 3)(a² x b)
(64)(a¹⁺¹ x b) - (24)(a²b)
64a²b - 24a²b
40a²b

A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

The volume of a cube is height x length x width:

v = h x l x w
v = 9 x 1 x 3
v = 27

A rectangle is a parallelogram containing four right angles. Opposite sides (a = c, b = d) are equal and the perimeter is the sum of the lengths of all sides (a + b + c + d) or, comonly, 2 x length x width. The area of a rectangle is length x width. A square is a rectangle with four equal length sides. The perimeter of a square is 4 x length of one side (4s) and the area is the length of one side squared (s²).

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 1 + 1 + 6 + 8
p = 16