We can see that the series starts with six 5's, then the terms are multiplied by 4 each time. So, the common ratio is 4.
Now, let's write the series in a more compact form:
$$5 + 5 + 5 + 5 + 5 + 5 + 4 + 16 + 64 + 256 + 414$$
$$= 6(5) + 4 + 4^2 + 4^3 + 4^4 +
Show more…