Bob wants to build a pyramid out of legos with 3 levels where the bottom level has 7 legos per side and each level has one less lego per side than the level below it. How many legos total will he need?
First find the total number of legos on the bottom layer: 7 legos * 7 legos = 
<gadget id="calculator">7*7</gadget>
<output>49</output>
49 legos.
Then find the number of legos per side on the next layer: 7 legos - 1 lego = 
<gadget id="calculator">7-1</gadget>
<output>6</output>
6 legos.
Then find the total number of legos on the second level: 6 legos * 6 legos = 
<gadget id="calculator">6*6</gadget>
<output>36</output>
36 legos.
Then find the number of legos per side on the top level: 6 legos - 1 lego = 
<gadget id="calculator">6-1</gadget>
<output>5</output>
5 legos.
Then find the total number of legos on the top level: 5 legos * 5 legos = 
<gadget id="calculator">5*5</gadget>
<output>25</output>
25 legos.
Then add the number of legos on each level to find the total number of legos: 49 legos + 36 legos + 25 legos = 
<gadget id="calculator">49+36+25</gadget>
<output>110</output>
110 legos.

<result>110</result>