Mathematica Tutor

Part 6: Current values of variables

1. Enter
   z=3*s*t+2
   Now assign the value 7 to s and the value 1 to t.
   s=7
   t=1
   Then enter
   z
   to see the current value of z.
   
   
2. Go back up to the line
   s=7
   and change the 7 to 8. Then press SHIFT-RETURN while the cursor is still in this line. Again note that an altered line must be entered for the altered value to be acknowledged by Mathematica. Similarly, change the value of t to -1. Now enter
   z
   again.

We repeat: Mathematica remembers what has been entered in the order it was entered.