某些语言中有一个函数叫做 eval(string)

;(function () {
    var str = readline();
    if (str.match(/[^\d\.\(\)\+\-\*\/]/g))
        return print("FormulaException");
    str = "var k = "+str;
    if (str.match(/[^\d\.]0\d/g) ||
            str.match(/[\*\/\+\-][\*\/\+\-]/g) ||
            str.match(/((\D\.\d)|(\d\.\D)|(\D\.\D))/g))
        return print("FormulaException");
    try {
        eval(str);
    } catch (e) {
        return print("FormulaException");
    }
    if (isNaN(k) || k == Infinity || k == -Infinity)
        return print("ZeroException");
    print(k.toFixed(2));
})();

from decimal import Decimal

s = input()
if len(s)>1 and s[0]=='0' and (s[1] not in '.+-*/'):
print ('FormulaException')
elif any(st in s for st in [sig1+sig2 for sig1 in '+-*/' for sig2 in '+-*/'] +
[sig+'0'+num for sig in '+-*/()' for num in '0123456789'] +
[x for x in 'abcdefghijklmnopqrstuvwxyz']):
print( 'FormulaException')
else:
try:
print (Decimal(eval(s)).quantize(Decimal('0.00')))
except ZeroDivisionError:
print ('ZeroException')
except SyntaxError:
print( 'FormulaException')
except NameError:
print ('FormulaException')
except ValueError:
print ('FormulaException')

与 @SW_Wind 的方法一样

from decimal import Decimal

s = raw_input()
if len(s)>1 and s[0]=='0' and (s[1] not in '.+-*/'):
    print 'FormulaException'
elif any(st in s for st in [sig1+sig2 for sig1 in '+-*/' for sig2 in '+-*/'] +
                         [sig+'0'+num for sig in '+-*/()' for num in '0123456789'] +
                         [x for x in 'abcdefghijklmnopqrstuvwxyz']):
    print 'FormulaException'
else:
    try:
        print Decimal(eval(s)).quantize(Decimal('0.00'))
    except ZeroDivisionError:
        print 'ZeroException'
    except SyntaxError:
        print 'FormulaException'
    except NameError:
        print 'FormulaException'
    except ValueError:
        print 'FormulaException'