One simple way to calculate the perimeter of a circle is to multiply its radius by two and further multiply the product by pi. You need a ruler and a divider to accomplish this task.
- Measure the radius
Take the divider, and stretch it from the center of the circle to any point on the circumference. Transfer the divider to the ruler, and read the measurement. Do not tamper with the stretch of the divider during the transfer to avoid getting an inaccurate measurement. The measurement you get is the radius of the circle. Use a string to measure the radius if the distance from the center of the circle to its circumference is longer than the stretch of the divider.
- Multiply pi by two
Multiply the value of pi, which is 3.142, by two to get 6.284. You can make the value of pi 22/7 to make the calculation process easier if it involves fractions.
- Calculate the perimeter
Multiply the product of pi and two with the radius of the circle to get the perimeter. For instance, if the radius of the circle is 10 centimeters, the perimeter of the circle is the product of 6.284 and 10, which is 62.84 centimeters.