Final answer:
The circumference of Leslie's button is approximately 25 mm, calculated using the formula C = 2πr with the radius of 4 mm and rounding to two significant figures.
Step-by-step explanation:
The circumference of Leslie's button can be found using the formula for the circumference of a circle, which is C = 2πr, where r is the radius of the circle and π (pi) is approximately 3.1415927. Since Leslie's button has a radius of 4 millimeters, we simply plug this value into the formula to calculate the circumference.
Therefore, the circumference of Leslie's button is C = 2 × 3.1415927 × 4 mm = 25.1327412 mm. Because the radius was given to two significant figures, we should also express our answer to two significant figures, so the circumference is approximately 25 mm.