tentry() and tans() are very simple TIGCC programs that return a previous answer/entry from the Home screen history area, but, unlike the built-in ans()/entry() functions, they will retrieve the top-most entry, not the most recent one.
I sometimes find it more productive to recall answers from the top.
Contrary to its built-in counterpart, tans() ids do not change (unless you delete an entry from the middle of the stack). This makes tans() very useful to refer to previously entered expressions. You won't need to store the answers in variables, just write down the equation number[1] and invoke it using tans() the next time you need it.
[1]: The number assigned to last entry is shown at the bottom right of a TI-89 calculator. BTW, you can change the capacity of stored entries from the default 30 to 99: press <diamon>+|.