- if you are tuning to the key of D, then the note D would be "1" as you count on your fingers with the alphabet... and the fifth (5) from there would be A (D, E, F, G, A). That's the 1 (the tonic or key note) and its 5th note in the scale... D with A. Hence the popular tuning DAA.
Those irritated by grain of sand best avoid beach.
-Strumelia proverb c.1990