yu gonna kount 0,000,000 as a goog 7-digit number?
then yu hav 0,000,002,...004,...006, & so on
that be arithmatik sequens, with start=0, step=2, & number terms=9,999,998/2
=4,999,999
sum=24,999,995,000,000
but if yu start with sumthun like 1,000,000, yu get differ number