variables variable is an identifier that stores value operators operators are used to combine expressions into more complex expressions for examplein the operators and are used the python operators for numbers include the usual arithmetic operations of addition (+)subtraction (-)multiplication (*)division (/)and exponentiation (**the python output statement print displays the values of series of expressions to the screen in pythonassignment of value to variable is done using the equal sign (=using assignmentprograms can get input from the keyboard python also allows simultaneous assignmentwhich is useful for getting multiple input values with single prompt definite loops are loops that execute known number of times the python for statement is definite loop that iterates through sequence of values python list is often used in for loop to provide sequence of values for the loop one important use of for statement is in implementing counted loopwhich is loop designed specifically for the purpose of repeating some portion of the program specific number of times counted loop in python is created by using the built-in range function to produce suitably sized list of numbers exercises review questions true/false the best way to write program is to immediately type in some code and then debug it until it works an algorithm can be written without using programming language programs no longer require modification after they are written and debugged python identifiers must start with letter or underscore keywords make good variable names expressions are built from literalsvariablesand operators in pythonx is legal statement python does not allow the input of multiple values with single statement counted loop is designed to iterate specific number of times in flowchartdiamonds are used to show statementsand rectangles are used for decision points