user2835: In chapter 4 of Arduino Workshop on page 85 (or page 31 in the pdf) it says that the voltage at AREF in the schematic is given by: 
Vin * R2 / (R2 + R1)
However, the voltage is flowing from 5V to Ground so isn't AREF actually in parallel with R1, and so shouldn't AREF be given by:
Vin * R1 / (R1 + R2) ?

user83: You are correct.
$$V_{ref} = \dfrac{R_1}{R_1 + R_2} \cdot V_{CC}$$
or Vref = Vin * R1 / (R1 + R2) until we finally get MathJax enabled on this site.

2835: <p>In <a href="https://docs.google.com/viewer?url=http%3A%2F%2Fwww.nostarch.com%2Fdownload%2Fsamples%2FArduinows_ch4.pdf" rel="nofollow">chapter 4</a> of Arduino Workshop on page 85 (or page 31 in the pdf) it says that the voltage at AREF in the schematic is given by: </p>

<p>Vin * R2 / (R2 + R1)</p>

<p>However, the voltage is flowing from 5V to Ground so isn't AREF actually in parallel with R1, and so shouldn't AREF be given by:</p>

<p>Vin * R1 / (R1 + R2) ?</p>
 83: <p>You are correct.</p>

<p>$$V_{ref} = \dfrac{R_1}{R_1 + R_2} \cdot V_{CC}$$</p>

<p>or Vref = Vin * R1 / (R1 + R2) until we finally get <a href="https://arduino.meta.stackexchange.com/questions/13/is-there-an-easy-way-to-enter-formulas-in-questions">MathJax</a> enabled on this site.</p>
