please help

The sum of the first  n  even numbers   =    n ( n + 1)  

We have 250  even numbers  from  2 to 500  inclusive  

So....the sum of these  = 250 * 251   =  62750      (1)

The  sum  of the  even numbers from  2 to 8 inclusive  =  the sum of the first four even numbers =  4 * 5  = 20  (2)

So....the sum of the even numbers  between 10 and 500 inclusive  =  (1)  - (2)  =  

62750 -  20   =

62730

so we have (10+500)*(500-10/2+1)/4=510*496/4=63240