<image> Cut out 4 small squares with a side length of ______ $$cm$$ from a square with a side length of $$10cm$$ along the thick solid line, and piece them together to form a large square that serves as the base of a right rectangular prism; fold the remaining part along the dashed lines to form an open-top right rectangular prism; finally, piece the two parts together to form a complete right rectangular prism, with its surface area equal to the area of the original square.