The approximation indicator "≈" I take advantage of for decimal approximations with tilde "~" currently being a rougher approximation. While the algebraic system for $b, c$ is simple to calculate, the algebraic formulation for $a$ is very hard to compute. For this reason the modern method relies on numerical calculation https://tarot-bizum09894.blogrelation.com/42658231/the-fact-about-por-qué-es-bueno-leer-el-tarot-that-no-one-is-suggesting