Bob has planted corn in his garden, and it has just started to sprout. A week after planting it, it had grown 2 inches. The next week, its height increased by twice as much as it had the first week. In the third week, it grew 4 times as much as it did the week before. How tall are the corn plants now?
The second week it grew twice as much as the first week, so 2 * 2 inches = 
<gadget id="calculator">2*2</gadget>
<output>4</output>
4 inches.
The third week it grew 4 times as much as in the second week, so 4 * 4 inches = 
<gadget id="calculator">4*4</gadget>
<output>16</output>
16 inches.
In total, it grew 2 inches + 4 inches + 16 inches = 
<gadget id="calculator">2+4+16</gadget>
<output>22</output>
22 inches.

<result>22</result>