While loops capture the scenario of looping until a specified event happens (like a repeat-until in Scratch). The first action of execution in a while-loop is checking whether the event is already satisfied. A flowchart as shown below is an intuitive representation (some students find it helpful to understand the flow of execution). 
Example 1 showed how to print the numbers from 1 to 99 using a for-loop. Here is the same problem using a while loop:
number = 1 while number < 100: print(number) number = number + 1
Examples 6, 7, and 8 present three problems that are naturally solved using a while loop.
Example 6: Sum up the digits in an integer
