Brain EaserPuzzles and brain teasers involving basic arithmetic and other simple math concepts – very little math knowledge required!
In matchstick puzzles, you are presented with an incorrect equation made using matchsticks, and you must move 1 or more matchsticks to turn it into a valid equation.
You must use all of the matches, and you are not allowed to make an inequality symbol such as ≠, ≥, >, <, or ≤.
Try these 7 fun matchstick equation puzzles!
7 + 2 = 9
Move exactly 2 matches to make this a valid equation.
Bonus: find two different solutions.
In matchstick equation puzzles, you are not allowed to make an inequality symbol such as ≠, ≥, >, <, or ≤. That would make it too easy!
What is the most frequent digit among the numbers between 1 and 1000 (inclusive)? Consider only base-10 whole numbers.
What two numbers contain no zeroes and can be multiplied together to produce 100000?
Some consider Friday the 13th (any Friday that falls on the 13th day of a month) unlucky.
In a calendar year, how many Friday the 13th can occur? Find both the minimum and maximum.
| 13 | |||
| 10 | |||
| 4 | 16 | ||
| 7 |
The cells in this 4×4 grid puzzle contain the numbers 1-16 each once. There are two rules to the arrangement of the numbers:
Fill in the remaining numbers.
Rearrange exactly 2 matches to make this a valid equation.
In matchstick math puzzles, you are not allowed to make an inequality symbol such as ≠, ≥, >, <, or ≤. That would make it too easy!
I like the numbers 4 and 5. I like to add 4’s and 5’s together to make other numbers, such as 4 + 4 + 5 + 5 + 5 = 23. How many numbers from 1 to 1000 can be written as the sum of 4’s and 5’s?
A man wants to enter an exclusive club, but doesn’t know the password. He observes a few other patrons:
Thinking he has figured it out, the man walks up and the doorman says “10”. The man replies “5” but it’s incorrect and he is turned away.
What should the man have said instead?
Move exactly 1 match to make this a valid equation.
In matchstick math puzzles, you are not allowed to make an inequality symbol such as ≠, ≥, >, <, or ≤. That would make it too easy!
What is the smallest number you can make by moving exactly 2 matches above?
I am thinking of a 3-digit number. When you reverse the digits of this number, you get a bigger number, and if you add that to the original number, the sum is 463. What was the number I was thinking of?
Move exactly 1 match to make this a valid equation.
Bonus: find two different ways to solve this.
In matchstick math puzzles, you are not allowed to make an inequality symbol such as ≠, ≥, >, <, or ≤. That would make it too easy!
A kid is adding consecutive integers on a calculator, one at a time, starting with 1 + 2 + 3 + … and so on. At one point you notice the sum is now 100, but that shouldn’t be possible if the kid was adding this way. The kid tells you that he made an error and subtracted exactly one of the numbers he was supposed to add.
What is the number he subtracted?
Can you arrange eight eights so that the numbers add up to 1000?
Jake has a 4-digit number in mind and asks Raj to guess the number. Raj can have 7 guesses, and Jake will give him some hints after 6 guesses.
Raj makes these 6 guesses:
These were all wrong, but Jake says every guess had exactly one (and only one) correct digit in the correct position. Additionally, all the digits are different.
What should Raj’s 7th guess be?
The U.S. uses 5-digit zip codes to help determine where mail goes. Since mail can be oriented in all sorts of directions, they avoid assigning zip codes that could be confused with a different zip code when read upside-down. For example, 61666 could be confused with 99919 when upside-down, so mail could be accidentally routed to the wrong zip code if both were actual zip codes.
How many zip codes could be confused with a different zip code when read upside-down?
In the example above, 61666 and 99919 would count as two confusing zip codes. Also, zip codes are allowed to start with 0, such as 00501.
How many times do the hour and minute hands meet on an analog clock every day? What are those times?
Make the following line a valid equation using only these mathematical operators: addition, subtraction, multiplication, division, parentheses, exponentiation, square root, and factorial.
2 2 2 2 = 50
Which perfect square of a 4-digit number has the same last four digits as the original number?
How do you use 3, 3, 8, and 8 to make 24?
Each number must be used exactly once, and only addition, subtraction, multiplication, division, and parentheses can be used.
What is the biggest number you can make by moving exactly 2 matches in the number above?
Assume that numbers must be represented in their standard “digital clock” font (for example, a “1” requires two segments).
Swap two of the digits in this equation to make it a valid equation:
7 x 7 + 9 x 9 = 138
Three friends decide to split the cost of hiring a cleaner. The agency charges them $30, so they each hand over a $10 bill.
Later the agency discovers the rate was actually $25 instead of $30. They send the cleaner with $5 to reimburse the friends.
It’s hard to split $5 three ways, reasons the cleaner, so he gives the friends $1 each, and keeps $2 for himself as a tip.
But wait – each friend paid $9, for a total of $27, and the cleaner pocketed $2. That’s 27 + 2 = 29, whereas they originally handed over $30. Where did the missing dollar go?
The missing dollar riddle is a classic, well-known riddle of unclear origin – usually with a clerk and a room bill or a waiter and a restaurant bill. But it’s simple yet tricky, and may trip up even savvy puzzle-solvers.