What is a letter or symbol in math?

Answer 1

A letter is a character used in the Roman or Greek alphabet.Symbols are special mathematical characters which are used for

• arithmetical operations, such as +, - , * and /;
• the decimal point and thousand separators;
• the radical symbol,
• comparisons such as <, > and the non-strict equivalents, and =;
  
• special characters such as the capital Sigma and Pi to indicate sums or products of sets of numbers,
• special characters to denote different kinds of integration.