The approximation signal "≈" I take advantage of for decimal approximations with tilde "~" being a rougher approximation. $begingroup$ I feel a very good to start with e book is 'A First Program in Mathematical Examination' by David Alexandar Brannan and may advise it and also a number of that https://tarotdejesus72592.myparisblog.com/36966791/the-smart-trick-of-por-qué-es-bueno-leer-el-tarot-that-no-one-is-discussing