There are 10 red, yellow and white balls of the same size and shape in a bag, at least how many balls must be taken out to get the red ball.
一个袋子中有大小形状相同的红、黄、白三种颜色的小球各10个，至少要拿出多少个球，才能一定拿到红球．
<gadget id="calculator">10 + 10 + 1</gadget>
<output>21</output>

<result>21</result>