One yard equals 3 feet if each side of a square is 1 yard long then what is the perimeter of the square in feet?

Oh, dude, a yard is 3 feet, so if each side of the square is 1 yard long, that's just 3 feet. The perimeter of a square is the sum of all its sides, so with all sides being 3 feet, the perimeter is 3 + 3 + 3 + 3 = 12 feet. Easy peasy, lemon squeezy!