This tool is used to evaluate arithmetic expressions containing mixed numbers (e.g. 2 1/3), proper and improper fractions, integers, brackets, and the operators + − × ÷.
3 1/5), fractions (7/8), integers (-4), parentheses,
          and operators + - */× ÷.
          Examples: 2 1/3 + 4 1/2, (1 1/2 + 3/4) × 2, -2 1/3 ÷ 1/6.