Markdown is not LaTeX.
To compile me, run this in R:
See output here.
A paragraph here. A code chunk below (remember the three backticks):
##  2
.4-.7+.3 # what? it is not zero!
##  5.551115e-17
It is easy.
Yes I know the value of pi is 3.1415927, and 2 times pi is 6.2831853.
Sigh. You cannot live without math equations. OK, here we go:
\(\alpha+\beta=\gamma\). Note this is not supported by native
markdown. You probably want to try RStudio, or at least the R package
markdown, or the function
You can write code within other elements, e.g. a list
foo is good
strsplit('hello indented world', ' ')[]
##  "hello" "indented" "world"
bar is better
Or inside blockquotes:
Here is a quote, followed by a code chunk:
x = 1:10 rev(x^2)
##  100 81 64 49 36 25 16 9 4 1
Nothing fancy. You are ready to go. When you become picky, go to the knitr website.