Symbols of quantity, such as: I, 2+i, A, X, natural logarithm base E, pi. Plus sign (+), minus sign (-), multiplication sign (× or), division sign (÷ or/), union of two sets (∩), intersection (∩), root sign (√), logarithm (log, lg, ln), ratio (. Relational symbols such as "=" are equal signs, "≈" are approximate signs, "≦" are unequal signs, and ">" is greater than the sign.