A zoo has 21 penguins and twice as many polar bears?  How many total animals do they have?
There are 21*2=
<gadget id="calculator">21*2</gadget>
<output>42</output>
42 polar bears.
So the total 21+42=
<gadget id="calculator">21+42</gadget>
<output>63</output>
63 total animals.

<result>63</result>