1. **Problem statement:** Mr. Old Mac Donald wants to build three fences numbered 1, 2, and 3 around a green square grass carpet that measures 2 meters by 2 meters. We need to calculate the length of wire netting required for each fence. 2. **Understanding the problem:** The grass carpet is a square with side length 2 meters. 3. **Formula for perimeter of a square:** The length of wire netting needed for each fence is the perimeter of the square, given by: $$\text{Perimeter} = 4 \times \text{side length}$$ 4. **Calculate the perimeter:** $$\text{Perimeter} = 4 \times 2 = 8$$ meters 5. **Interpretation:** Each fence surrounds the same square area, so each fence requires 8 meters of wire netting. **Final answer:** Each fence requires 8 meters of wire netting.