A number includes only two powers of 10 and is more than 100 000

It is neither a simple arithmetic nor geometric sequence, since it involves both a ratio and a difference.for  week "n", 40% of the previous week's bottles were sold, so 60% is what's left, so what's left = f(n-1)*(1-40%)=0.6f(n-1).48 bottles arrive, so we add 48 to what remains this week, givingf(n)=0.6*f(n-1)+48