Entropy of SCs 4–23. The entropy estimates for SCs 10–23 (black dots) are based on daily sunspot number data, whereas those for SCs 4–9 (red dots) are obtained from Eq. (6). Note the coincidence of the least entropy values with the well known Dalton minimum. The entropy values obtained from the F10.7 flux and solar magnetic field for SCs 19–23 (black plus symbol) and SCs 22–23 (magenta cross) are also shown. The entropy values obtained from the solar magnetic field (B₀) and F10.7 flux (Φ_s) are respectively multiplied by 0.77 and 1.24 to view them on a common scale.