You can use the v helper macro to get values from your IEx history.
iex(1)> a = 1
1
iex(2)> b = 2
2
iex(3)> a + b
3
iex(4)> v(-1) # Retrives expression values relative to the current one
3
iex(5)> v(2) # Retrieves expression values using an absolute index
2