Octaves double from one octave to another, so start with octaves beginning with the number one, for example:
1 doubled is 2, 2 doubled is 4, 4 double is 8 and then we go on to this sequence:
1,2,4,8,16,32,64,126,256,512,1024,2048,etc,etc
Find one of the numbers near a range, so for example on this chart Ethereum was trading at 190.31. That price is in between the octaves of 126 and 256. The number I use as the low for the indicator is 126.