How many can you solve? Brain-flexing math riddle quiz
Math is truly fascinating! It’s not just about calculation drills—there are rules and puzzles you can use in everyday life hidden within it.
Here, we’ve gathered math quizzes that nurture children’s thinking skills and number-based riddles that spark inspiration, all designed to make learning fun.
From intuitive, illustration-based questions to logical problems where you fill in the blanks with numbers, we’ll share the full appeal of math.
There might even be some problems that adults surprisingly can’t solve.
Gather the whole family and dive in together with excitement!
How many can you solve? Brain-flexing math riddle quiz (1–10)
[Math Quiz] What number goes in the blank?
Do you know the Arithmetic (Math) Olympiad, where people around the world compete in their mathematical abilities? Here’s a fill-in-the-blank problem from the 2019 trial that lets you experience its atmosphere.
You’re given a grid with 4 rows and 7 columns.
It contains the numbers 1 through 5, but three cells near the center are blank—try filling them in.
What makes this problem interesting is that it doesn’t rely on adding or dividing numbers; it calls for a flash of insight.
[Math Quiz] How many horse mackerels are there?
![[Math Quiz] How many horse mackerels are there?](https://i.ytimg.com/vi/bp4fZSDW2Yk/sddefault.jpg)
Here’s a quiz about shopping titled “How many horse mackerels?”.
The quiz features a woman who has come to shop.
She buys at least one of each of seven types of fish and pays 3,600 yen.
What we know of the breakdown is: fish A costs 130 yen, fish B costs 170 yen, fish C costs 78 yen, and fish D costs 104 yen.
From this, let’s figure out how many of fish B she bought.
This problem actually appeared in the Math Olympiad and is quite complex.
It’s said that even among University of Tokyo students, the correct answer rate was only about 19%.
[Math Quiz] Using 4-minute and 7-minute hourglasses, measure 9 minutes.
![[Math Quiz] Using 4-minute and 7-minute hourglasses, measure 9 minutes.](https://i.ytimg.com/vi/exODWA1SVKk/sddefault.jpg)
It’s a simple yet tricky puzzle: using a 4-minute and a 7-minute hourglass, measure 9 minutes.
If you just use the 4-minute and 7-minute hourglasses, a total of 11 minutes would pass.
So the key to this problem is how to measure 7 minutes.
For those who are having trouble finding the answer, here’s a hint.
If you flip both the 4-minute and 7-minute hourglasses at the same time, the 4-minute hourglass will run out first.
At that point, the 7-minute hourglass will have 3 minutes’ worth of sand remaining.
A calculation quiz where you look at the illustration and answer
A visually engaging calculation quiz where you answer by looking at illustrations.
In this quiz, you examine equations that combine illustrations with numbers to derive the answer.
For example, an equation might state that “adding the horse illustration three times equals 30,” and based on that, you figure out what each illustration represents in the combined equations.
For instance, if the equation is “adding the horse illustration three times equals 30,” then 30 ÷ 3 shows that each horse illustration represents 10.
[Rule Quiz] What number goes in the blank?
![[Rule Quiz] What number goes in the blank?](https://i.ytimg.com/vi/BwIXtokHBQQ/sddefault.jpg)
Creativity is key! This is a quiz where you guess the missing number.
You’re shown a diamond shape containing four numbers, with one number on each of the top, bottom, left, and right sides.
There are four such diamonds in a row, and in the last one, the bottom number is blank—you need to fill it in.
If you notice the pattern from the other diamonds, you’ll solve it quickly.
The trick is to create a formula using the top and the two side numbers.
It’s surprisingly simple, and once you get it, it’s very satisfying.
[Math Quiz] How many balls are there in total?
![[Math Quiz] How many balls are there in total?](https://i.ytimg.com/vi/dK0zeH_N4t8/sddefault.jpg)
Would you like to try a quiz where you guess the total number of balls? In this puzzle, balls are arranged in a square and stacked in four layers, and you’re asked to give the total number as seen from directly above.
If you try to count them at a glance, the fourth layer hides the balls in the lower layers, so it doesn’t work well.
In other words, you need to figure out how many balls are in the parts you can’t see.
Here’s a hint: first, determine how many balls make up the square on the first layer.
You should be able to find it by counting the number of balls along the length and the width.
Puzzle: What word can be found by calculation?
Puzzle-solving games are fun, aren’t they? So let me introduce a math quiz with a strong puzzle-solving element.
You’ll be given several equations with answers, plus a fill-in-the-blank sentence.
First, solve the equations and draw lines connecting each equation to its answer.
Then, figure out the letters that go into the blanks.
The real twist of this problem is that solving the equations alone won’t give you the answer.
The hint lies in the shapes of the lines connecting the equations to the answers.
Look very closely—you’ll see a certain letter emerge.
[Math Quiz] 5-Yen Coin Savings
![[Math Quiz] 5-Yen Coin Savings](https://i.ytimg.com/vi/E2SfqU5cTnM/sddefault.jpg)
This is a 5-yen coin saving quiz that’s also effective as brain training.
In this quiz, there’s a boy who saves 5 yen every day.
Since his piggy bank was small, he would exchange coins as follows: when he had two 5-yen coins, he exchanged them for a 10-yen coin; when he had five 10-yen coins, he exchanged them for a 50-yen coin; when he had two 50-yen coins, he exchanged them for a 100-yen coin; and when he had five 100-yen coins, he exchanged them for a 500-yen coin.
Based on these conditions, let’s determine the coin amounts at specific counts.
The trick is to think in terms of the smallest possible denominations.
Math Quiz: What are the ages of the five siblings?
High difficulty! Here’s a puzzle to determine the ages of five siblings.
In this quiz, you’ll figure out each of their ages.
The only information given is the sums of the ages of pairs of siblings.
There are 10 sums in total, each representing the sum of two different siblings’ ages.
Using these, let’s uncover how old each sibling is.
The key to solving this problem is that the eldest is older than the second eldest, and the second eldest is older than the third.
Keep that in mind as you set up equations and plug in the numbers.
Insert ‘+’, ‘-‘, ‘×’, and ‘÷’ to complete the equation!
Let me introduce a relatively basic fill-in-the-blank puzzle.
You’re given blanks and numbers, and your task is to insert +, −, ×, or ÷ to complete the equation.
It’s not just about calculating—the key is flexible thinking.
By the way, this type of fill-in-the-blank quiz appears in various problems on YouTube and in books.
It’s perfectly fine to enjoy using those.
Some of them even ask you to complete quite complex equations.