There are 60 wooden blocks of the same shape and size in the cloth bag, and every 6 blocks are coded with the same number, so at least how many blocks can be taken out at a time to ensure that at least three of them have the same number.
布袋中有60个形状、大小相同的木块，每6块编上相同的号码，那么一次至少取出多少块，才能保证其中至少有三块号码相同．
<gadget id="calculator">60 / 6</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

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

<result>21</result>