A simple method is used to calculate; 2008-2-4-6-8. - 98-1000

A simple method is used to calculate; 2008-2-4-6-8. - 98-1000

It should be 2008-2-4-6-8. - 98-100
Original formula = 2008 - (2 + 100) X50 / 2 = 2008-2550 = - 542