A pocket contains 10 balls of three different colors, red, yellow, and blue. At least how many balls must be drawn, and there must be 10 of the same color.
一个口袋装有红黄蓝三种不同颜色的小球各10个，至少要摸出多少个小球，肯定有10个颜色相同的．
<gadget id="calculator">9 * 3</gadget>
<output>27</output>

<gadget id="calculator">27 + 1</gadget>
<output>28</output>

<result>28</result>