User blog comment:B214/Question and Answers 4/@comment-24502975-20141102214513/@comment-16281343-20141103011339

Demonic power doesn't use calculations. It may look like it but in only needs imagination and have a good sense.


 * Teleportation using demonic power - What is needed  for a person to teleport to another place is for the coordinates to be known beforehand and be inputted in their magic circle. An example is :
 * Gremory group teleporting to their clients' location. They know the location of the client because of the flyers that they gave out.
 * This rule is the same with teleportation with magic.
 * IMO, once a coordinate is input in the magic circle in can easily be remembered to use for teleportation once again. Think of it as a phone book. All the coordinates are there and you can just choose where to go.
 * In Rias' case where he teleported to the wrong place, like what I've said above, a person needs to have good sense; and in this case, Rias was distracted because of what happened to her all day. That's why she messed in teleporting (picked a wrong coordinate).

Now, for magic, remember that magic is derived from the demonic powers of the devil. They have to substitute the lack of demonic power with equations.