This task illustrates the first activity in the IET Puzzle Panels. The student (or student team) is required to understand the workings of a flowchart.
Remembering the panels have to be applicable to all ages and abilities, the task can be altered to match the target group. For example, young children will be given a start point and a start value and need to calculate the end value after working through the flow chart. But how can the task be made challenging for university level students? The examples above show how the task is altered to significantly increase the level of difficulty whilst keeping the arithmetic simple.
You will notice the flowchart has no start point! The task is to find an entry point (a pink block) to which the supplied number is applied. Choosing the correct cell will give the final result in the blue circle after working through the flowchart. There is only one correct cell. One small complication (a simplification really) is that after a division, drop the fraction. For example, -7 divided by 2 is not -3.5 but should be truncated to -3.
Like all the Puzzle Panel tasks, the students can succeed by guesswork or trail and error (though the penalty is time); teamwork is also possible, a group of 4 students could quickly test 7 possible solutions each by working forwards through the flowchart. However, employing an intelligent strategy is more effective! It is possible to solve the puzzle quickly by working backwards from the end until a block consistent with the initial value is encountered. The difficulty is that a number range has to be carried backwards. For example, if you come out of a divide by 7 box with 4, the numbers going in could have been any integer in the range 28 – 34.
Warning: it is possible to have very long loops where a number is progressively changed until an exit condition is met!
Try the nine examples above which use the same flowchart structure. The difficulty level is moderate.