Telephones - filament

4
4/3 = 1.3
= 2
1.3/2 = 0.66
2 @ 0.66

Go other way

2/0.66 = 1.3
1.3/3 = 4

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Not this: because 2 @ 0.33 = 1 @ 0.66
4

4/3 = 1.3
= 2
r 0.66
0.66/2
= 2 @ 33%