If each term in the sum a1+a2+a3+.....+an is either 7 or 77 and the sum equals 343, which of the following could be equal to n?  Choose the correct choice from the following answers.
A) 38 B) 39 C) 40 D) 41 E) 42
Since, there is no 49 in the answer choices (343/7 = 49), we know there is at least one 77.   343 - 77= 
<gadget id="calculator">343 - 77</gadget>
<output>266</output>
266   266/7= 
<gadget id="calculator">266/7</gadget>
<output>38</output>
38   38+1= 
<gadget id="calculator">38+1</gadget>
<output>39</output>
39.   If 39 wasn't there, I would have subtracted 77 from 266 and continued in a similar way.   Ans.39
<result>B</result>
If each term in the sum a1+a2+a3+.....+an is either 7 or 77 and the sum equals 343, which of the following could be equal to n?