computing with formulas interest py in regular terminal or run interest py in an ipython window or spyder the interest py program is not much more complex or useful than the helloworldexample from the previous but there are couple of important differences firstnotice thatin this case we did not use quotation marks inside the parentheses this is because we want python to evaluate the mathematical formulaand print the result to the screenwhich works fine as long as the text inside the parentheses is valid python codeormore preciselya valid expression that can be evaluated to produce result if we put quotation marks around the formula abovethe code would still workbut the result is not what we want try itat this pointit is also worth noting thatwhile we stated above that python is flexible and high-level languageall programming languages are extremely picky about spelling and grammar considerfor instance the line write( *( + , / )^ while most people can read this line quite easilyand interpret it as the same formula as the one aboveit makes no sense as python program there are multiple errorswrite is not legal python word in this contexta comma has another meaning than the decimal pointand the hat does not mean exponentiation we have to be extremely accurate with how we write computer programsand it takes time and experience to learn this the mathematical formula above is evaluated according to the standard rules the terms are evaluated one by onefrom left to rightwith exponentiation performed first and then multiplication and division we use parentheses to control the order of the evaluationjust as we do in regular mathematics the parentheses around ( means that this sum is evaluated first (to obtain )and then raised to the power of forgetting the parenthesis and writing ** will produce very different resultjust as in mathematics because the use of parentheses to group calculations works exactly as in mathematicsit is not very difficult to understand for people with mathematical background howeverwhen programming more complicated formulas it is very easy to make mistakes such as forgetting or misplacing closing parenthesis this mistake is probably the most common source of error when programming mathematical formulasand it is worth paying close attention to the order and number of parentheses in the expressionseven for experienced programmers getting this principle wrong will lead to either an error message when the code is run or to program that runs fine but produces unexpected results the first type of error is usually quite easy to find and fixbut the latter can be much harder although python is quite strict on spelling and grammarin programming terms called the syntaxthere is some flexibility for instancewhitespace inside formula does not matter at all an expression like * works just as well as * generallywhitespace in python program only matters if it is at the start of linewhich we will return to later otherwiseone should