Datapunter
Further to the above i have just tried your solution to 2.3 in JCreator, saved the file as c

java\Lesson23, compiled it and then executed it but it to did not print the values on screen.
First, don't worry about where you are in the course, everybody does it in his own time, some fast and some take a bit longer. Doesn't matter.
The problem you had is simply a matter getting to know the language and learn how to think as a programmer. Perfectly normal.
Please check Lesson23.java again, just tried it and it showed 900 and 100 , did you get an error ? mail me.