Finding perimeter is easiest with squares. Perimeter is the distance around the outside of the figure. There are two good ways to find the perimeter. The first and longer method of finding perimeter is simply to add up the length of each side. Thus, we would take the length of top of the square and add it to the length of the right side. We'd continue all the way around. The formula for this method could be written like so: 

top + right side + bottom + left side = perimeter.

Since a square has equal sides all around, we could also write the formulalike so:

\(\displaystyle s+s+s+s=perimeter\)

The second and easier way of finding perimeter for a square is a simplification of the first method. Instead of adding the same number four times we could simply multiply by 4. Written as a formula, this would look like this:

\(\displaystyle 4\ \times \ s=perimeter\)

For the this question, your work should then look like one of these two options:

\(\displaystyle 15.5cm + 15.5cm + 15.5cm + 15.5cm = 62.0 cm\)

or

\(\displaystyle 15.5cm \times 4 = 62.0 cm\)

Finding perimeter is easiest with squares. Perimeter is the distance around the outside of the figure. There are two good ways to find the perimeter. The first and longer method of finding perimeter is simply to add up the length of each side. Thus, we would take the length of top of the square and add it to the length of the right side. We'd continue all the way around. The formula for this method could be written like so: 

top + right side + bottom + left side = perimeter.

Since a square has equal sides all around, we could also write the formulalike so:

\(\displaystyle s+s+s+s=perimeter\)

The second and easier way of finding perimeter for a square is a simplification of the first method. Instead of adding the same number four times we could simply multiply by 4. Written as a formula, this would look like this:

\(\displaystyle 4\ \times \ s=perimeter\)

For the this question, your work should then look like one of these two options:

\(\displaystyle 16.2cm + 16.2cm + 16.2cm + 16.2cm = 64.8 cm\)

or

\(\displaystyle 16.2cm \times 4 = 64.8 cm\)

The perimeter of a shape is the distance around the outside boundry of that shape.

In order to find the perimeter, add up the lengths of the sides of that shape.

Because the sides of a square all have the same length, add \(\displaystyle 5+5+5+5\). Equivalently, multiply the side length by the number of sides: \(\displaystyle 4*5=20\).

Because perimeter measures length, the unit of the answer should be inches, not inches².

The perimeter of a square is four times its sidelength, so a square with perimeter 64 inches has sides with length 16 inches. Use the area formula:

\(\displaystyle A = s^{2} = 16^{2} = 256\)

A square that has an area of 81 has sides that are the square root of 81 (side² = area for a square).  Thus each of the four sides is 9.  The sum of three of these sides is \(\displaystyle 9 + 9 + 9 = 27\).

A cube comprises six faces, each of which is a square. To find its total surface area, find the area of one face by squaring its sidelength:

\(\displaystyle 3 \frac{1}{2} \times 3 \frac{1}{2} = \frac{7}{2} \times \frac{7}{2} = \frac{49}{4} \textrm{ in}^{2}\)

Then multiply this by six:

\(\displaystyle 6 \times \frac{49}{4} =\frac{6}{1} \times \frac{49}{4} = \frac{3}{1} \times \frac{49}{2} = \frac{147}{2} = 73 \frac{1}{2} \textrm{ in}^{2}\)

A cube comprises six faces, each of which is a square. To find its total surface area, find the area of one face by squaring its sidelength:

\(\displaystyle 2.6 \times 2.6 = 6.76 \textrm{ cm}^{2}\)

Then multiply this by six:

\(\displaystyle 6 \times 6.76 = 40.56 \textrm{ cm}^{2}\)

A cube comprises six faces, each of which is a square. To find its total surface area, find the area of one face by squaring its sidelength:

\(\displaystyle 25 \times 25 = 625 \textrm{ in}^{2}\)

Then multiply this by six:

\(\displaystyle 6 \times 625 = 3,750\textrm{ in}^{2}\)

A cube comprises six faces, each of which is a square. To find its total surface area, find the area of one face by squaring its sidelength:

\(\displaystyle 12 \times 12 = 144 \textrm{ cm}^{2}\)

Then multiply this by six:

\(\displaystyle 6 \times 144 = 864\textrm{ cm}^{2}\)

Each side can be divided into three 3-foot sections.  This gives a total of \(\displaystyle 3\times3=9\) squares.  Another way of looking at the problem is that the total area of the large square is 81 and each smaller square has an area of 9.  Dividing 81 by 9 gives the correct answer.