Let's the last term is 999, not 1000.

The number of terms is: ( 999 - 1 ) : 2 + 1 = 500 terms ( from 1 -> 999 )

The sum of the terms from 1 -> 999 is:

( 999 + 1 ) X 500 : 2 = 250000

The sum of this sequence is:

250000 + 1000 = 251000

The sum is: 251000

There are 30 male students.

There are 4 right angles of a square.