To complete a series means looking at it in succession and working out what is missing. Being able to do this is a vital part of 11-Plus Non-Verbal Reasoning, so make sure that you have mastered it before moving on.
If you are working through the quizzes in order, you have reached the end of the 'Complete the Series' questions. Well done! Just think of all you've learned along the way. There is always a great sense of satisfaction in finishing something really difficult so give yourself a pat on the back.
Colin Powell was a very famous general in the United States. He said that, "A dream doesn't become reality through magic; it takes sweat, determination and hard work."
So congratulate yourself at having reached this point. All of your efforts are now paying off and you should enjoy the last in this set of quizzes.