There are 20 red socks, 30 blue socks, and 40 white socks in a bag, all of the same size. You can ensure that there are at least 10 pairs of socks in the socks (two pairs of the same color). Only socks are a pair).
一只袋子中有20只红袜子，30只蓝袜子，40只白袜子，大小都一样，不用眼睛看至少摸出多少只袜子，才能保证摸出袜子中至少有10对袜子(颜色相同的两只袜子为一对)．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">2 * 9</gadget>
<output>18</output>

<gadget id="calculator">3 + 1 + 18</gadget>
<output>22</output>

<result>22</result>