salary table

[gipi100]

hi, i have a salary table look like this

ID grade point amount incrementby
1 A1 P1 1000
2 A1 P2 1100
3 A1 P2 1210

how do i want to make a difference(in incrementby column) between ID 1 and
ID 2; ID 2 and ID 3,

thanks

 

[KARL DEWEY]

If this is a one time shot then Excel does an excellent job - =D3-D2