The Kangaroo Math Contest: How Children Prepare — and Why Mental Arithmetic Helps
On a Thursday morning in March, well over 800,000 children in Germany alone sit down in front of the same booklet at the same time. No calculator, no book, no formula sheet — just scratch paper and 75 minutes. This is the Kangaroo of Mathematics, the largest maths competition in the world, and for a great many children it is their first encounter with mathematics that does not feel like school.
The question parents ask us most often about it: can you even prepare for this? The honest answer is: not the way you prepare for a school test. There is no syllabus to work through. But there are two things you can do, and both help noticeably.
🦘 What the Kangaroo actually is
It is a multiple-choice contest: every problem comes with five answers, exactly one of which is correct. It is written on a single day, in the same form across Europe and beyond, and it takes place in the child's own school rather than at some unfamiliar venue.
In Germany it is organised by Känguru e. V. at the Humboldt-Universität zu Berlin together with the German Mathematical Society. It traditionally runs on the third Thursday in March — in 2027 exceptionally on 8 April, because the usual date falls into the Easter holidays. Registration goes through the school, normally online between 1 December and 31 January. From 184 participants in 1995 it has grown to more than 880,000 in 2025.
In Switzerland the contest is run by the association «Känguru Schweiz»; the next date is 18 March 2027. The fee is CHF 3.– per child. Scratch paper is the only aid permitted. From class 7/8 upwards, taking part as a team is also possible.
📊 How many problems, how much time
| Grade level | Germany | Switzerland |
|---|---|---|
| Grades 3/4 | 24 problems · 75 min | 18 problems · 45 min |
| Grades 5/6 | 24 problems · 75 min | 24 problems · 60 min |
| Grades 7/8 | 30 problems · 75 min | 30 problems · 75 min |
| Grades 9/10 | 30 problems · 75 min | 30 problems · 75 min |
| Grades 11–13 | 30 problems · 75 min | 30 problems · 75 min |
The organisers' official pages are always the binding source — dates, fees and rules change from year to year. Links are at the bottom.
Work the arithmetic out for your own child once. In grade 3 in Germany that is a little over three minutes per problem; in Switzerland, two and a half. It sounds generous. It is not — not if part of that time goes on reassembling 7 × 8.
🧠 It is not an arithmetic test — which is exactly why arithmetic counts
This is the point most parents get backwards at first. Kangaroo problems are puzzles. They do not test whether a child has memorised the times tables. They test whether the child can see through a situation: rotate a shape in their head, find an ordering, rule a case out systematically, spot the pattern in a sequence.
From which many people conclude that practising arithmetic does nothing for the Kangaroo. That conclusion is wrong, and the reason is the same one as in reading.
A child's working memory is small. A child who has to stop halfway through a line of reasoning to work out 6 × 7 very often loses the line of reasoning itself. Not because of the multiplication — but because the multiplication has taken the space the thought was sitting in. We describe exactly this mechanism at length for reading in our article on reading fluency in 1st and 2nd grade. In mathematics it holds unchanged.
The reverse holds too. A child for whom the basic operations run automatically — retrieved rather than computed — has their whole head free for what the Kangaroo is actually about. They read the problem, think, try a second idea when the first one does not carry, and after three minutes still have room to breathe.
Secure mental arithmetic does not win the contest. It makes it possible for the thinking to happen at all.
📝 How to practise sensibly
The most effective preparation is unspectacular and costs nothing:
- Do old problems. Both organisers publish past problems with solutions. Nothing prepares a child for Kangaroo problems like Kangaroo problems.
- One run against the clock. Two or three weeks beforehand, do one complete past round under real conditions. Not to grade it, but so that the feeling of the time limit is not a new experience on the day.
- Practise skipping. The most common avoidable defeat is a child who sinks their teeth into problem 9 and never lays eyes on problem 22, which they would have solved in a minute. A problem may be left and come back to later.
- Eliminate answers. With five given answers, thinking about the answers is often faster than computing. Estimate the order of magnitude, cross out the impossible ones, check odd against even — this is a skill in its own right, and it can be learned.
- Ten minutes a day beats two hours on Sunday. For mental arithmetic as for everything else.
- No calculator. It is not allowed in the contest. Practice should mirror that.
🎮 Where Math Fighter fits in
To be clear before we start. Math Fighter has no connection to the Kangaroo of Mathematics. The app is not official preparation material, it contains no contest problems, and it is neither licensed by nor affiliated with the organisers. «Kangaroo of Mathematics» and the associated names and logos belong to their respective owners. So we are expressly not claiming that Math Fighter teaches the contest. We are saying something more modest: it is a great way to prepare — because it trains precisely the thing that frees a child's head up on the day.
Problems in a similar style: the Way of the Warrior lessons
Anyone who looks at real Kangaroo problems spots the pattern immediately: short, self-contained thinking problems, five answers, and the actual work is not in the calculation but in seeing through it. The Way of the Warrior lessons in Math Fighter are cut in a similar shape — small problems you reason through in your head instead of grinding out by a procedure. That is not a substitute for contest practice. But it is the same kind of thinking, and a child who is at home in that kind of problem is not startled by the format in March.
School mode: targeted at your child's own grade level
The Kangaroo is tiered by grade, and the problems for 3/4 assume something quite different from those for 7/8. Math Fighter has school mode for this, with its own learning path by grade level: the child practises what is actually needed at their level, instead of grinding through material that arrives two years early or two years late. When preparation time is limited, that is the difference between targeted and accidental practice.
Private lessons: working on the topics that genuinely stick
Every child has one or two places where they get stuck — division with remainders, fractions, percentages, rearranging an equation. Those are exactly where the time goes on contest day. The AI tutor in Math Fighter gives private lessons: it identifies where the child is stuck, explains step by step instead of only reporting right or wrong, and then keeps practising that specific thing. That is the most efficient preparation there is, because it works on the two topics that are actually slowing the child down.
The Dojo: the basics, drilled to automaticity
Dojo mode runs from the white belt (addition, subtraction) through orange (times tables, division, percentages) and blue (fractions, decimals) up to the black belt (equations, algebra). How the belt system is built up is described on our page about the maths basics. For the Kangaroo only one thing about it matters: each belt is practised until it sits. And what sits costs no attention in March.
Speed under pressure
Concentrating on arithmetic for 75 minutes straight is an unfamiliar demand for a child. The duels in Math Fighter — against the computer, against a sibling, online — train exactly that: answering correctly under time pressure without it feeling like an exam. That is the part you cannot practise with worksheets.
🎮 Try Math Fighter
Mental arithmetic in short duels, Dojo belts from times tables to algebra, a learning path by grade level, and an AI tutor for the topics that stick. For children aged 6 to 16.
📅 Eight weeks out: a realistic plan
- Weeks 1–2: Ten minutes of mental arithmetic a day. Basics only, speed only. No contest problems yet.
- Weeks 3–4: Keep the ten minutes, and add three to five old Kangaroo problems twice a week — no clock, unhurried, together if your child likes.
- Weeks 5–6: Tackle the topics that visibly wobbled. A private lesson is worth more here than more puzzles.
- Week 7: One complete past round against the clock, under real conditions. Then look at it together: where did the time go?
- Week 8: Very little. A few problems for fun, an early night, a normal breakfast. Learning something new the evening before achieves nothing.
🚀 And the actual point
Every participant in the Kangaroo receives a certificate, the problem booklet to work through afterwards, and a small puzzle prize. That is not an accident but a design decision: the contest is not built to sort children, it is built to show them, once a year, mathematics that surprises them.
If your child comes out of the contest wanting to tell you which problem was the most beautiful one, the day was a success — whatever the score was. Preparation should make that experience possible, not replace it. And the best contribution to it is a child for whom the arithmetic comes so easily that there is room left over to be amazed.
📚 Official pages
- Känguru der Mathematik e. V., Humboldt-Universität zu Berlin — mathe-kaenguru.de (Germany: dates, registration through the school, past problems)
- Verein «Känguru Schweiz» — kaenguru-schweiz.ch (Switzerland: dates, registration, problem archive)
EduGameGalaxy and Math Fighter are independent of the organisers of the Kangaroo contest. All trademarks mentioned belong to their respective owners.