These are the Math Kangaroo video solutions for grades 11 to 12 for the 2023 Math Kangaroo exam. I'm Aditya Gupta and I'm the Math Kangaroo national champion. So the Math Kangaroo format has 30 problems in 75 minutes. Problems 1 to 10 are 3 points. Problems 11 to 20 are 4 points and problems 21 to 30 are 5 points. Obviously as the contest gets harder, as the problems get worth more, they also tend to get much harder. Top ranked scorers win prizes and may get both national and state level recognition in the Math Kangaroo contest. So for these video solutions, first I'm going to be reading the problem. Then I'm going to show you the multiple choice answer choices because they're a big part of the problem itself and can help you narrow down the way to find the solution and sometimes directly depend on the choices. I want you to pause the video at this point and try solving the problem on your own. And then we're going to have detailed explanations of the solution to each problem on this contest. And a lot of the times, depending on the problem, I'll also have some insights as to how you can solve it quicker given that it's multiple choice or given that you're solving this in a contest or how you can easily check your answer, just extra tidbits that might help you on your contest taking journey. And then finally, I'll end the video with the correct answer to the question. So before I move into the questions, just some general contest tips. First, always read the question slowly. If you read the question fast, you're going to save 10 seconds, but eventually you're going to end up losing those five point questions because you forgot to read that it says non-negative instead of positive or something silly like that, that would just not happen if you took the question just a bit more slowly. Now there's no penalty for guessing, so never be afraid to make educated guess. And if you can't make educated guess, if you have no clue, just make a random guess, right? I mean, there's a one fifth chance that you're correct. And if you're stuck on a problem, but you're not on a time crunch yet, you don't want to make a guess right now. You can maybe circle a guess, but maybe not bubble it in. Just move on and come back later at the end of the contest. Maybe when you have more time or when you're stuck on the harder problems. For the video solutions, if you get stuck on my explanations, try re-watching the videos. Sometimes it just helps to pause and think about my solution and then redo that same solution, re-watch it. If you still want more details, check out the official written solutions on the contest to see more details. All right, on to the problems.

Math Kangaroo

Aditya Gupta

exam solutions

problem-solving strategies

grades 11 and 12