The Sum of first N consecutive odd integers is N^2. What is the sum of all odd integers between 9 and 39 inclusive.
Choose the correct choice from the following.
A) 351 B) 384 C) 410 D) 424 E) 450
We're dealing with a sequence of CONSECUTIVE ODD INTEGERS: 9 to 39, inclusive. We're asked for the SUM of this group.   1) Start with the sum of the smallest and the biggest:   9 + 39= 
<gadget id="calculator">  9 + 39</gadget>
<output>48</output>
48   2) Now look at the 'next smallest' and the 'next biggest': 11 + 37= 
<gadget id="calculator">11 + 37</gadget>
<output>48</output>
48   Now we have proof that there is no middle term. We have 8 bunches of 48   8(48)= 384   384
<result>B</result>
The Sum of first N consecutive odd integers is N^2. What is the sum of all odd integers between 9 and 39 inclusive.