How to calculate 204-198 + 192-186 +... 24-18 + 12-6?

How to calculate 204-198 + 192-186 +... 24-18 + 12-6?

204-198+192-186+...24-18+12-6
=(204-198)+(192-186)+.+(24-18)+(12-6)
=There were 204 / 6 = 34 items in 6 + 6 +. + 6 + 6, with 2 items as a group, a total of 34 / 2 = 17 groups
=6*17
=102