I am a paranoid about symmetry. Especially with my feet and hands.
With my hands it is along the X,Y and Z axes. If I make an action with my hand where in my hand pointing along an imaginary X axes, I HAVE TO make the same action along the Y and Z axes relative to the X axis.
With my feet(which is limited in movement compared to my hands) the symmetry is with respect to 45degrees axis on the X-Y plane.
If i go to sleep on one side, and if I do wake up, i turn over to maintain symmetry.
I remember phone numbers by thinking of deep, intricate links between the numbers and positions of the numbers- with the logic mostly involving prime numbers.
I multiply numbers using the overs concept. Let me explain. If you ask me 42*7, in my mind it is 42 overs is 252 balls + 42 runs for runrate of 7, so 294.
I usually change the gear of my bike when the Tacho meter needle and the speedometer needle is almost parallel.