3 medium envelopes are placed in a large envelope, and 6 small envelopes are placed in each medium envelope, how many envelopes are there in total?
一个大信封中放3个中等信封，每个中等信封中又放6个小信封，一共有多少个信封．
<gadget id="calculator">6 * 3</gadget>
<output>18</output>

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

<result>22</result>