For any positive integer n, the sum of the first n positive integers equals n(n+1)/2. What is the sum of odd all the integers between 1 and 50?
Options
A) 500 B) 625 C) 750 D) 550 E) 600
numbers are 1,3,5-------,47,49   Average of the set: (largest+smallest)/2=(49+1)/2= 
<gadget id="calculator">(49+1)/2</gadget>
<output>25</output>
25;   # of terms: (largest-smallest)/2+1=(49-1)/2+1= 
<gadget id="calculator">(49-1)/2+1</gadget>
<output>25</output>
25   The sum= 25*25= 
<gadget id="calculator">25*25</gadget>
<output>625</output>
625   Answer: 625
<result>B</result>
For any positive integer n, the sum of the first n positive integers equals n(n+1)/2. What is the sum of odd all the integers between 1 and 50?