Inversions
Moving the root up (or down) an octave. Here we are keeping it inside the octave (closed).

Interval number	Interval quality
Unison <-> Octave	Major <-> Minor
2nd <-> 7th	Perfect <-> Perfect
3rd <-> 6th	Augmented <-> Diminished
4th <-> 5th	Tri-tone <-> Tri-tone

Interval numbers always add up to 9.

Unison <-> Octave

Minor 2^nd <-> Major 7^th

Major 2^nd <-> Minor 7^th

Minor 3^rd <-> Major 6^th

Major 3^rd <-> Minor 6^th

Perfect 4^th <-> Perfect 5^th

Tri-tone <-> Tri-tone

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