review exercises you can nd the solutions to these exercises and many other bonus resources online at realpython com/python-basics/resources write program that idle won' run because it has syntax error write program that crashes only while it' running because it has runtime error create variable in pythonvariables are names that can be assigned value and then used to refer to that value throughout your code variables are fundamental to programming for two reasons variables keep values accessiblefor exampleyou can assign the result of some time-consuming operation to variable so that your program doesn' have to perform the operation each time you need to use the result variables give values contextthe number could mean lots of different thingssuch as the number of students in classthe number of times user has accessed websiteand so on giving the value name like num_students makes the meaning of the value clear in this sectionyou'll learn how to use variables in your codeas well as some of the conventions python programmers follow when choosing names for variables the assignment operator an operator is symbolsuch as +that performs an operation on one or more values for examplethe operator takes two numbersone to the left of the operator and one to the rightand adds them together