The approximation indication "≈" I take advantage of for decimal approximations with tilde "~" being a rougher approximation. $begingroup$ I feel a good 1st reserve is 'A First System in Mathematical Evaluation' by David Alexandar Brannan and may recommend it together with a number of that have by now been https://johnathanmkrja.blogolize.com/5-essential-elements-for-por-qué-es-bueno-leer-el-tarot-75355231