Find the sum of the first five terms of a geometric series with a1 = 0.28, a5 = 362.88 and r = 6

The sum of a geometric series is given by:
Sn=[a(r^n-1]/(r-1)
the nth term is given by 
an=ar^(n-1)
From the information given:
a1=0.28, r=6
the sum of the first 5 terms will be:
s₅=[0.28(6^5-1)]/(6-1)
s₅=[0.28(7776-1)]/5
s₅=2177/5
s₅=435.4