Column A37 - A81: pH (independent variable in the math) - 40 values from 0 to 14

Column B37 - B81. Hydrogen ion concentrations [H]   =10^(-pH)

Column CA37 - A81: Calculated base volumes Vb (dependent variable in the math)
=(-((Va*(B37^5-Ca*B37^3*K1a+B37^4*K1a-2*Ca*B37^2*K1a*K2a+B37^3*K1a*K2a-3*Ca*B37*K1a*K2a*K3a+B37^2*K1a*K2a*K3a-B37^3*Kw-B37^2*K1a*Kw-B37*K1a*K2a*Kw-K1a*K2a*K3a*Kw))/((Cb*B37+B37^2-Kw)*(B37^3+B37^2*K1a+B37*K1a*K2a+K1a*K2a*K3a))))

where B37=Hydrogen ion concentrations [H], Va=Volume of acid;  Ca=molar concentrations of acid, Cb=Concentration of base (titrant), K1a, K2a, and K3a are the three acid constants of the acid.

Columns H and I: Vb and pH arranged for reverse plotting (xy scatter plot).