evaluate ( 51 + 52 + 53 + . . . + 100 )
sn = ( 1 + 2 + 3 + . . . + 50 + 51 + 52 + . . . + 100 ) - ( 1 + 2 + 3 + . . . + 50 ) = ( 50 x 101 ) - ( 25 x 51 ) = ( 5050 - 1275 ) = 3775 . option a
multiply(divide(add(100, 51), const_2), subtract(51, const_1))