At k = 2k₀:
E drops by 25/3 ≈ 3.17×Not 2×, not 4× — exactly 25/3. The exponent is precisely −5/3 across 4 orders of magnitude.
Drag the ruler on the chart to measure rise/run in the inertial subrange. Lock onto the red curve to verify slope = −5/3 ≈ −1.667.