Question

The sum of the even numbers between 77 and 535 is how much less than the sum of the odd numbers between78 and 536?

Answer 1

The sum of the even numbers between 77 and 535 is:

$78+80+82+\ldots+530+532+534=70074$

Now, the sum of the odd numbers between 78 and 536 is:

$77+79+81+\cdots+531+533+535=70380$

Thus, the sum of the even numbers between 77 and 535 is 306 less than the sum of the odd numbers between 78 and 536 because

$70380-70074=306$