A classroom needs 620 pieces of square bricks with a side length of 0.2 decimeters. How many pieces will be needed if the square bricks with a side length of 0.4 decimeters are used instead?
一间教室用边长0.2分米的方砖要620块，如果改用边长0.4分米的方砖要多少块？
<gadget id="calculator">0.2 * 0.2 * 620</gadget>
<output>24.8</output>

<gadget id="calculator">0.4 * 0.4</gadget>
<output>0.16</output>

<gadget id="calculator">24.8 / 0.16</gadget>
<output>155</output>

<result>155</result>