The floor of the classroom is covered with floor tiles. If rectangular floor tiles with an area of 40 square decimeters are used, 90 pieces are needed. How many square floor tiles with a side length of 6 decimeters are used instead?
教室地面贴地砖，如果用面积为40平方分米的长方形地砖，需要90块．如果改用边长是6分米的正方形地砖，需要多少块？
<gadget id="calculator">40 * 90</gadget>
<output>3_600</output>

<gadget id="calculator">6 * 6</gadget>
<output>36</output>

<gadget id="calculator">3_600 / 36</gadget>
<output>100</output>

<result>100</result>