Mix 30 balls of red, yellow, white, and blue in a jar, how many balls must be drawn out of the box to ensure that there are at least 6 balls of the same color? Answer: how much.
将红、黄、白、蓝四种颜色的球各30个，混放在一个罐盒里，请问至少要从中摸出多少个球，才能确保至少有6个同色的球？答案：多少．
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

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

<result>21</result>