hi every one


i need your help plz

in my program ther are 2 dropdown list

how can i find total of numbers between any 2 numbers i selected from drop down list

for ex:
i select number 2 from list 1
and i select number 8 from list 2
how can i find total of numbers between (1-8 )
i mean 3+4+5+6+7

????