Martin is casting three bells for the church's belfry. The first bell takes 50 pounds of bronze, the second bell is twice the size of the first bell, and the third bell is four times the size of the second bell. How much bronze does he need total?
First find the size of the second bell: 50 pounds * 2 = 
<gadget id="calculator">50*2</gadget>
<output>100</output>
100 pounds.
Then find the size of the third bell: 100 pounds * 4 = 
<gadget id="calculator">100*4</gadget>
<output>400</output>
400 pounds.
Then add the amount of bronze used for each bell to find the total: 100 pounds + 400 pounds + 50 pounds = 
<gadget id="calculator">100+400+50</gadget>
<output>550</output>
550 pounds.

<result>550</result>