There is a cuboid pool in the cafeteria, which is 36 decimeters long, 25 decimeters wide and 20 decimeters high. Lay tiles on the bottom and four walls of the pool, each tile is 4 square decimeters, how many tiles should be bought at least?
食堂有一个长方体水池，长36分米，宽25分米，高20分米．在水池底面和四壁铺瓷砖，每块瓷砖是4平方分米，至少要买多少块瓷砖？
<gadget id="calculator">36 * 25</gadget>
<output>900</output>

<gadget id="calculator">36 * 20 * 2</gadget>
<output>1_440</output>

<gadget id="calculator">25 * 20 * 2</gadget>
<output>1_000</output>

<gadget id="calculator">900 + 1_440 + 1_000</gadget>
<output>3_340</output>

<gadget id="calculator">3_340 / 4</gadget>
<output>835</output>

<result>835</result>