It is expected that the Under 9 age group will have only 7 and 8 year olds. Return from Get Fit for Badminton to Jake Downey's Biography, Badminton Books and Articles. The even numbers are 0, 2, 4, 6, 8, 10, 12, and so on. Use a beeping birdie or a balloon with a pure drag trajectory. To be a knockout badminton player, you have won part of the best of three games of 21 points.