(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Let an (read 'a sub n') be the nth digit after the decimal point in 2pi+2e. Evaluate

SUM (n=1 to inf) an(.1)^n

(here, again, an is meant to be 'a sub n')

2. Relevant equations

As far as I can see, this is a partial sum of a geometric series. To find the nth partial sum (or, in other words the infinite sum) use a/(1-r) where a is the first term of the series (scalar multiple) and r is the ratio of the exponent of the general form for geo series: ar^n

3. The attempt at a solution

My attempt gave back to sn=1/9

I used: .1/1-.1

I guess I'm thinking about this incorrectly

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Partial Sums

**Physics Forums | Science Articles, Homework Help, Discussion**