There is a square field with a side length of 20 meters. If you lay a row of cement square bricks with a side length of 50 cm around its edge on the inside and outside, how many pieces are needed in total?
有一块边长为20米的正方形场地，如果绕着它的边沿在里面和外面各铺上一排边长为50厘米的水泥方砖，一共需要多少块？
<gadget id="calculator">0.5 * 2</gadget>
<output>1</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<gadget id="calculator">21 * 21</gadget>
<output>441</output>

<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<gadget id="calculator">441 - 400</gadget>
<output>41</output>

<gadget id="calculator">0.5 * 0.5</gadget>
<output>0.25</output>

<gadget id="calculator">41 / 0.25</gadget>
<output>164</output>

<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">19 * 19</gadget>
<output>361</output>

<gadget id="calculator">400 - 361</gadget>
<output>39</output>

<gadget id="calculator">39 / 0.25</gadget>
<output>156</output>

<gadget id="calculator">164 + 156</gadget>
<output>320</output>

<result>320</result>