find the next number in the sequence
12, 20, 40, 72, 116, 172 ? Choose the correct choice from the following answers:
A) 500 B) 250 C) 240 D) 350 E) 400
240   240   40 { diff   20 + 12= 
<gadget id="calculator">  20 + 12</gadget>
<output>32</output>
&gt;32 add to it}   72 { diff   32 + 12= 
<gadget id="calculator">  32 + 12</gadget>
<output>44</output>
&gt;44 add to it}   116 { diff   44 + 12= 
<gadget id="calculator">  44 + 12</gadget>
<output>56</output>
&gt;56 add to it}   172 { diff   56 + 12= 
<gadget id="calculator">  56 + 12</gadget>
<output>68</output>
&gt;68 add to it}   240
<result>C</result>
find the next number in the sequence
12, 20, 40, 72, 116, 172 ?