A red brick is 25 cm long and 15 cm wide. What is the minimum number of red bricks needed to form a square?
一块红砖长25厘米，宽15厘米，用这样的红砖拼成一个正方形最少需要多少块．
<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<result>15</result>