# Questions tagged [arithmetic]

For puzzles involving addition, subtraction, multiplication, or division.

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### Pairs of Bogotá Numbers

A Bogotá number is a positive integer equal to some smaller number, or itself, times its digital product, i.e. the product of its digits. For example, 138 is a Bogotá number because 138 = 23 x (2 x 3)....
335 views

### Remember the 60s? Far-out man!

Can you convert the following to my unusual currency? 1.25, 1.75, 2.75, 3.25 Having done that, can you explain why some people think the smallest of these is somehow the biggest - at least as far I'm ...
177 views

### What's one and one and one and one and [closed]

Good morning. Today I am going to test your mental arithmetic. To do so I shall ask you to give me the sum of a series of ones. I shall say One and one and one and one and one and one, etc. Of course ...
746 views

### Smallest integer whose first n multiples contain the digit 1

For some time now I have been investigating the function $M(n)$, the least integer such that the first $n$ multiples of $M(n)$ contain the digit $1$. Thus $M(3) = 51$, because $51$ is the smallest ...
613 views

### The numbers on blackboard

The numbers $2020,2019,2018,...,1$ are written on the blackboard from left to right. John repeats the following process until there is only one number left: John chooses the first two numbers from ...
179 views

### Swapping the first and last digits of an integer

Take any n-digit integer (n > 1) and interchange its first and last digits. If neither of these is 0, and they are different, does it happen infinitely often that the resulting number is a multiple ...
6k views

### 9-5=5? Matchstick problem

Move one matchstick to make an equality. Question made by me (Is this too easy?)
676 views

### A Covid-19 puzzle: Alcohol for your School!

You are the principal of a primary school in HK. Schools are resuming soon, and you have to ensure that your school have enough alcohol. Each of the 30 classrooms should have a bottle containing 500mL ...
1k views

### Some numbers are more equivalent than others

[Second part and bounty challenge appended in May 2020]           ALL ANIMALS ARE EQUAL    BUT ...
122 views

### Numbers Relation Puzzle

I've written a numbers relation puzzle, I'd like to share it with you and see what you fellas think. ------ Try to find the relation between the numbers------ Good to know: there are 2 parameters ...
1k views

### Confusion on a math puzzle

One of my colleagues asked me below puzzle, Three friends went to a picnic. 1st and 2nd friends collected woods for cooking where 3rd friend did not participated because he was sick. 1st friend ...
185 views

### The death prism

One day, you are caught by a evil wizard. He presents you with a prism, and says, "You can ask me to turn this prism to any $n$-angled right prism. Then you shall fill in $1$ to $3n$ with no ...
303 views

### Find the missing number from the pyramid

? 1 3 3 3 9 9 3 1 9 Find the missing number in the pyramid?
33 views

### Use all of the following symbols and numbers in one equation for the result to be equal to 10 [duplicate]

Use all of the following symbols and numbers in one equation for the result to be equal to 10 (14, 12, 9 , 7, 3) (÷ × - +)
142 views

### Make the numbers 1-100 using 8 8s

Rules: Make the numbers 1-100 using eight 8s Use the operations + - * / exponentiation and ! No Rounding as in $(\sqrt{88}+8*8+8+8+8)/8= 12$ No using other digits Multi digit numbers ...
173 views

### Make the numbers 1-100 using six 6s

Rules: Make the numbers 1-100 using six 6s Use the operations + - * / exponentiation and ! No Rounding as in $((6 - (6 + 6) / 6) + 6!!) / 6 = 9$ No using other digits Multi digit ...
88 views

### What could be the answer of this maths puzzle? [closed]

Found this puzzle online. Tried many possible combinations of numbers with multiplication, addition etc. Has anyone ever solved this?
4k views

### Help solving a math puzzle table

I am struggling to find the answer. Here is the source: math logic puzzle phone app.
317 views

### Make the numbers 1-50 using the digits 2, 0, 2, 0

Try to make all the numbers from 1-50 using 2, 0, 2, 0 exactly once. Rules: Use only the operations +, -, *, /, !, exponents and square root No rounding eg. ...
3k views

### Brain Testing Logical Reasoning Puzzle

Can you answer this logical puzzle? Puzzle Source: https://www.funwithpuzzles.com/2018/12/brain-testing-logical-reasoning-puzzle.html
231 views

### NineFind - Which 9 Numbers Are Correct?

Text Version: ...
18k views

### Make numbers 1-30 using 2, 0, 1, 9

This is very similar to the 2, 0, 1, 8 problem. Just try to make all numbers 1-30 using the digits 2, 0, 1, 9. Rules: Use all four digits exactly once Allowed operations: +, -, x, ÷, ! (factorial), ...
447 views

### Can you decipher these ancient numerals?

This stone was found at the foot of an ancient door. This old note with some mathematical relationships was discovered nearby. Can you use this information to figure out what number each of the 9 ...
265 views

### Missing numbers

The hexagon below is almost complete but there are 3 missing numbers. Try replace the question marks! Hint Hint2: Hint3
290 views

### Catching the thief before it's too late

London, 17:15. Inspector Arbor wasn't quite happy with the current situation. Normally, he would have enjoyed this sunny Saturday outside at the Park but now wasn't the time for that. Valuable ...
638 views

### This new puzzle type needs a name {5}

I believe I have invented a new type of puzzle... What is its name? Colour-blind-friendly version available here. Begin by solving the 9x9 sudoku; each of the 9 symbols ...
229 views

### One Step Forward, Two Steps Back

What is the next number in this never-ending sequence? 0 1 1 110 111 101 11000 11101 10101 1100110 1001011 ...
715 views

### What is a Trio Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it a Trio Word™. Use the ...
269 views

### Find the number that does not fit into the pattern shown below

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 12 34 56 78 910 1112 1314 1516 1718 1920 2122 2324 2526 2728 2930 3132 3334 3536 Each row forms a set which implements a pattern. The two patterns ...
1k views

### Primes less than 100 in a 4 x 4 board

Place one of the digits (0 to 9) in each of the cells of a 4 x 4 board so that as many as possible of the 25 primes less than 100 divide at least one of the 10 positive 4-digit numbers that can be ...
286 views

### Happy birthday Ramanujan!

On December 22 2019, Ramanujan would have been 132 years old. In his memory here are two puzzles around 132. In the six vertices of each of these graphs place six positive integers that add up to ...
357 views

$(A)72$ $(B)18$ $(C)9$ $(D)19$ Source:My coaching DPP The question asks you identify the pattern and find the missing character. I have been trying to solve this problem from a long time but I ...
98 views

### Highest scoring words based on distance travelled along the alphabet v2

This is a follow on from my previous word puzzle: Highest scoring words based on distance travelled along the alphabet The twist in this puzzle which opens it up a lot more is that the alphabet can ...
460 views

### Highest scoring words based on distance travelled along the alphabet

For any word we define it's alphabetic distance to be the total amount of places in the alphabet you need to traverse between each letter. Example: WORD has a score of 25 8 character distance ...
221 views

### How do I solve this problem?

I am trying to answer this puzzle - which of the five potential answers is correct, and why? This test comes from Metropol iq1 book
3k views

### Longest word worth at most a million

An old and popular puzzle, recently revived on Twitter by Alex Bellos, Chris Smith, and others, asks to take the first 26 primes, relate each to letters of the alphabet (A = 2, B = 3, C = 5, ..., Y = ...
159 views

### Free Assignment: Longest Word Worth a Million

This is very much inspired by this question. Take the first 26 primes and relate each one to a letter of the alphabet. On this occasion, you may choose how each number is mapped to each letter (...