A tile is 15cm long and 13cm wide, and a square floor needs to be laid. How many tiles are needed at least?
一块瓷砖长15cm，宽13cm，需要铺一个正方形的地面，至少需要多少块瓷砖？
<gadget id="calculator">13 * 15</gadget>
<output>195</output>

<gadget id="calculator">13 / 195</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">15 * 13 * 15 * (1/15)</gadget>
<output>195</output>

<result>195</result>