7. As shown in the figure, fold an A4 paper along the midpoints of its two longer sides, and you will get 2 smaller rectangles. The ratio of the length to the width of the smaller rectangles is the same as that of the A4 paper. If the length of the A4 paper is 29.7 cm, then the area of the square with the width of the A4 paper as its side length is $\qquad$ square centimeters (accurate to one decimal place).
Analysis:
The two rectangles have the same length-to-width ratio, so $b: a=a: 2 b$, thus $a^{2}=2 b^{2}, 2 b=29.7 \text{ cm}, 2 b^{2}=29.7 \times 29.7 \div 2=441.045 \text{ cm}^{2}$. Since the answer should be accurate to one decimal place, the answer should be: 441.0

Note: 441 is the wrong answer, the concept of retaining one decimal place is unclear