- Identify that the
**perimeter** of the rink is to be calculated.
- Write down the formula d · p + 2L – 2d = P
- Re-write the formula: change all of the letters into words, according to their meaning:

diameter x p + 2 x Length – 2 x diameter = perimeter

4. Re-write the formula: change all of the letters you can for actual given numbers:

Note: Leave out units of measure words. (eg. feet, cm)

20 x p + 2 x 50 – 2 x 20 = perimeter

- Calculate: 20 x p + 2 x 50 – 2 x 20 = 122.83185307

Note: Find and use the p button on your calculator. The calculator`s memory stores 20 digits for π, so calculations are highly accurate. Using the number 3.14 is much less accurate, often unacceptable in trades and engineering.

Your calculator`s circuitry may not be programmed with doing multiplications before addition and subtraction, so you may need to bracket the operation, like this: (see info on calculator steps further below)

(20 x p) + (2 x 50) – (2 x 20) = 122.83185307

If you calculator does not have brackets, do the multiplications separately, Take a pencil and write down the subtotals, then add and subtract like this:

20 x p = 62.83185307

+ 2 x 50 = 100

– 2 x 20 = 40

- Take a pencil and write down “rink perimeter = 122.8318”
- Write
*m *after the number 122.8318 Now you`re done with the math.
- The last step: check your work, make sure everything was copied and written correctly then determine that the correct way to write the answer is 122.8318 m

*Note: This calculation highlights the math for perimeter. It does not include material cutting and fitting considerations, available possible materials, fastener or other needs.*

Get a $20-or-so dual-display scientific calculator, even if you can`t take it with you into the exam hall. A calculator is also a learning tool, Technology Use is one of the 9 Essential Skills you can`t do without. Trying out different functions on a calculator will further your understanding and help with building a bigger mental picture. It builds links between numbers and algebra. It is important to try alternative calculations or approaches, to sketch & label angles, tracking changes to units of measure, visualizing to cross-link the concepts of perimeter and numbers.

Using a scientific calculator, do the following:

Press **(** button

Enter **20**

Press **x** (multiplication) button (this could be omitted, depending on your calculator`s circuits)

Press **p** button or **2ndF** button then the **p **button, depending on how your calculator is laid out.

Press **)** button

Press **+** button

Press **(** button

Enter **2**

Press **x** (multiplication) button

Enter **50**

Press **)** button

Press **– ** button

Press **(** button

Enter **2**

Press **x** (multiplication) button

Enter **20**

Press **)** button

Press **=**

** You should see 122.8318531 on your display.**