Could someone please help me understand this question? I was given this question today as part of a technical analysis, which I failed to answer. I am not sure what is expected? 
Is it really just a case of substituting the values at the bottom in place of ...? It seems unlikely. Can someone please explain the question to me?
1. Add up the numbers in the following series

17 + 34 + 51 + … + 71,417


a) 150047117
b) 170047117
c) 130047117
d) 160047117
e) 190047117

 A: $$17(1 + 2 \ldots 4201) = 17 (4201)(4202)/2 = 150047117$$
Note: It is making use of Gauss's formula for the sum of the 4201 numbers.
Approach


*

*You can see that there is a common factor of $17$ in the increasing number. 

*You can now factor (divide) the last number by $17$ and it gives $4201$. 

*Now, you need a formula to sum the first $4201$ numbers. 

*Thanks to Gauss, we have the sum of the first $n$ numbers as $\dfrac{n(n+1)}{2}$. 

A: The problem wants you to add up all the multiples of $17$ from $17\cdot1$ to $17\cdot4201=71,417$.  If you're a Gauss, you can see in an instant how to do this.  If you're not a Gauss, you might still realize that the sum must also be a multiple of $17$.  You might also notice that at most one of the offered answers can be a multiple of $17$, since they differ from one another by small multiples of $10,000,000$, which is not divisible by $17$.  So it suffices to see which one $17$ actually divides.
My pocket calculator won't allow $9$-digit numbers, which stymied me at first, until I noticed the $17$ at the end of each number.  So instead of looking at $150047117/17$, for example, it suffices to look at $1500471/17$.  Etc.  As soon as you get an integer quotient, you're done.
