org-mode/existing_tools/exp-blocks/example-for-r.org

#+BEGIN_R
a <- 3
a
#+END_R

- the value of a is \R{a}
- the value of a + 3 is \R{a + 3}  

#+BEGIN_R  hidden_block, echo=FALSE, results=HIDE
   a <- 3
   b <- 6
#+END_R