Calculate the perimeter of a rectangle whose width is 6 cm, and it is 2 times less than its length.

The perimeter is the sum of all side lengths. Since a rectangle has 4 sides, while the two sides are pairwise equal, we get the formula for the perimeter of the rectangle: P = 2 * (a + b) where P is the perimeter of the rectangle, a is the width of the rectangle, b is the length of the rectangle.

According to the condition of the problem, the width is 6 centimeters, while the length is 2 times less than the width, which means: 6 (cm) / 2 = 3 (cm).

Substitute the obtained values into the formula: P = 2 * (6 (cm) + 3 (cm)) = 2 * 9 (cm) = 18 (cm).

Answer: The perimeter of the rectangle is 18 centimeters.