Questions tagged [formation-of-numbers]

For puzzles about forming numbers using other numbers and mathematical operations. Use with [mathematics]

Filter by
Sorted by
Tagged with
4
votes
2answers
224 views

Seven 2s with seven math operations

Linked to A four digit number using exact same 4 digits A number with same repeated digits is called a Repdigit or Monodigit number https://en.wikipedia.org/wiki/Repdigit Can you write an equation for ...
-3
votes
1answer
203 views

Everything needed to solve this cipher is on Puzzling Stack Exchange [closed]

5444 ---> lcxxfy 1906 ---> pstbqjilj 1582 ---> tcxvbpixrpejooat 1431 ---> dohhsfb 888 ---> uvqta 605 ---> noacomputers 618 ---> ylibz 425 ---> ...
13
votes
6answers
4k views

A four digit number using exact same 4 digits

ABCD is a 4 digit number where A,B,C and D are 4 distinctly separate digits between 1 and 9. Using any of the following math operations and the digits A,B,C and D exactly once get the number ABCD. ...
4
votes
4answers
2k views

Make an equation from expression "1 4 9 100" [closed]

Fill the gaps of the expression $1$ $4$ $9$ $100$ with mathematical operations $+,-,*,/$, physical units and an $=$ sign, such that a correct equation is created. Example: expression $1$ $100$ $...
2
votes
1answer
146 views

Make 1-100 using 2 0 2 2

You may use the following: Addition [e.g. 2+2] Subtraction [e.g. 2-2] Multiplication [e.g. 2x2] Division [e.g. 2/2] Decimal point [e.g. 2+.2] Exponents [e.g. 22] {tetration is NOT allowed} Square ...
2
votes
5answers
399 views

Largest pair of consecutive numbers, not greater than a million, that can be expressed with four fours [closed]

What is the largest pair of consecutive numbers, not greater than a million, each of which can be expressed using precisely four fours and an assortment of standard operators (including concatenation, ...
-3
votes
6answers
271 views

Make 93 using 2, 0, 2, 2 and a least powerful set of operations [closed]

Use some mathematical operations to make an expression equal 93. You must use each one of the digits 2, 0, 2, 2 exactly once, and no other digits. To score the solutions, your set of operations used ...
4
votes
1answer
1k views

Find three ways of forming the number 100 using 3,3,5,7

As it says in the title. Rules: anything not explicitly allowed is forbidden. use 3, 3, 5, 7 and multiplication, division, sum, difference, unary minus, and exponentiation in any order. Parentheses ...
8
votes
3answers
621 views

Calculation - the hard way

This is a puzzle I love to play with my math students and I hope you will enjoy it too: You are given the numbers 1, 2, 3, 4, and 5 exactly once. Your target is a number, e.g. 36. Can you create a ...
-4
votes
1answer
118 views

How to open the lock from this safe?

The puzzle is as follows: The figure from below shows a lock mechanism used to store sensitive data microfilms from a certain lab. This mechanism is magnetic and consists in numbered buttons which ...
-4
votes
2answers
92 views

A challenge to make 1 - 100 [closed]

So this challenge is you have (don't have to) make the numbers 1 - 100 by using the numbers 1, 3, 4, 6 only once. I'm stuck on how to make 54. Can anyone help me? P. S. You can use +, -, ÷, x, ! And ...
11
votes
4answers
436 views

Not so boring numbers

This is inspired by this and this and more similar ones. Let us consider formation of a given positive integer N by the following rules You may use only one digit, which one is your choice and you ...
10
votes
4answers
2k views

Make 38 using the least possible digits 8

This is a follow up question to this one, which was: Make the number 1998 using the minimum amount of digits 8. Your allowed operations are +, -, *, /, ^, % (percent). You need not use only integers ...
1
vote
5answers
1k views

Make numbers 1 - 40 using digits 2, 0, 2, 1

Using only the digits in the year 2021 and basic mathematical operations (+, -, × and ÷), how many of the numbers from 1 to 40 can you make? Not all of the numbers are possible! You may use each digit ...
-4
votes
5answers
173 views

A Triad of Pies

Make the 41 integers between -20 and 20 (-20, -19, ..., 0, 1, ...20) using only the four basic arithmetical operations, square root, the floor function, and, Surprise Surprise, exactly 3 π’s. No more ...
3
votes
4answers
693 views

Make numbers from 1-10 with 5 3s

In this puzzle book, I came across a question that goes like this: Make the numbers from 1-10 using 5 3s. Rules: You are only allowed to use the four basic arithmetic operators ($+, -, \times, \div$...
2
votes
3answers
102 views

Form a magic square with assorted numbers

Arrange the following numbers in a way such that all rows, columns and the diagonals add up to the same number. ...
-4
votes
1answer
127 views

Use only πs to get e

I am taking this puzzle from inspiration from the Four Fours to get Pi puzzle. The puzzle rules are just slightly different. Here are the rules: You are trying to get as close to e as possible with ...
5
votes
2answers
120 views

Numbers side by side

Ok, so here's a little puzzle I got. I have five different numbers. They all have different amount of digits. If you place them side by side you see the number 32767 How is this even possible!? ...
7
votes
4answers
689 views

Sum of digits of sum of digits of sum of digits

The following question was asked in a competitive exam for which I am preparing and I was unable to solve it (in fact I am completely clueless about it). So, I am asking for help here. Given a number ...
4
votes
1answer
148 views

Constant puzzle

A constant is hiding behind this puzzle, can you tell which? 4 $\rightarrow$ 2 $\rightarrow$ 1 $\rightarrow$ 1 $\rightarrow$ 1 $\rightarrow$ $\dots$ ? $\rightarrow$ ? $\rightarrow$ ? $\rightarrow$ $\...
1
vote
1answer
78 views

Add operators to make the equation correct, and give 3 ways to do so

I'm trying to solve this puzzle: Add operators to make the following equation correct: 4 4 4 4 = 2. Give 3 ways to do so. You are allowed to use brackets if necessary, but no rearranging of numbers ...
7
votes
1answer
273 views

This puzzle's value is 334

The 28th of october is valued by 40. This sentence is valued by 17. This paragraph is valued by 143. This puzzle is valued by 334. Can you give the value of Puzzling StackExchange?
-3
votes
2answers
150 views

Using the number 8 6 4 2 = either 19 or 17 [closed]

The numbers can only be used once. You can use any operator from BEDMAS.
-2
votes
2answers
119 views

Using the numbers 8642 = 9 [closed]

Using any calculation in BEDMAS use the numbers 8645 = 9 Numbers can only be repeated once.
2
votes
0answers
177 views

Even and primes puzzle?

this is secret numbers that increase regularly, what is the order? If you like numbers, it will be fun. $2^3 \times224299$ $2^2 \times 3^2 \times 19 \times 3557$ $2 \times 5 \times 320647$ $2 \times ...
1
vote
4answers
309 views

Express numbers 1 - 100 using only 1, 2, 3, 4

The least number that cannot be written using the numbers 1, 2, and 3, each exactly once, and any combination of standard arithmetic operations (including factorials) is 41. What is the least such ...
-4
votes
4answers
299 views

876925431=2016 Use the four basic operators

Use the four basic operators ×, ÷, +, − and if you want brackets to make: 8 _ 7 _ 6 _ 9 _ 2 _ 5 _ 4 _ 3 _ 1 = 2016. You can use each operator as many times as needed. Concatenation is not allowed.
6
votes
7answers
1k views

Math Challenge: Create 8

Using only $2$, $7$, and $7$ (each one must be used only once) and only using the operations $+$, $-$, $\times$, $\div$, $\textrm{^}$, and parentheses, make 8. You can also use decimals.
1
vote
0answers
155 views

Smallest Unattainable Target in Letters and Numbers (Countdown in the UK)

To cheer myself up during the twin problems of (1) underperforming sports team XXX and (2) lockdown in state YYY, neither of which shall be named, I am doing daily number puzzles based on the show ...
7
votes
1answer
198 views

There are $3$ boxes with total $27$ balls. Find minimum number of steps to get to equal balls in each box

You have $3$ boxes $A, B$ and $C$. Boxes $A$ and $B$ are empty to start with and box $C$ has $27$ balls. In "$i$-th" move you make, you must transfer exactly "$i$" balls from one ...
7
votes
1answer
437 views

Can you find the number?

There's a number with the following characteristics: The hundreds digit plus the units digit minus the tens digit equals 8. 3 times the hundreds digit plus 2 times the tens digit minus the units ...
35
votes
6answers
5k views

too easy puzzle? Try it first!

Arrange the numbers $1$ to $9$ to replace letters $A$ to $I$ so: $(A+B+C+D)-(E+F+G+H) = I$ Too easy? Too many answers? Try it first! Then explain why.
5
votes
1answer
715 views

Formula One (?) Hard Puzzle

On a website I use to go, one of the writers gave this hard puzzle: What are the meaning of those numbers given they are not Norwegian coordinates. 60.6604211,10.7210713 I have no clue how to solve ...
4
votes
1answer
204 views

Find the missing numbers in these flowers

Can you figure out the pattern and solve for the three missing numbers? All petals and centers each contain a single digit. There is a unique solution for each missing number. Hint 1: Hint 2:
8
votes
2answers
309 views

Is there a root free solution for the 6s challenge?

So the 6s challenge consist of taking a number from 0 to 10 and, using only "common" operations and the number three times, obtaining the number 6. For example: $(0!+0!+0!)! = 6$ and $(4 - (...
24
votes
21answers
3k views

When you take away two

I am an odd number. When you take away two, I become even. What am I? Edit: @hexomino got my original answer but I have come up with another valid answer. Edit 2: @QuantumTwinkie got my other ...
6
votes
7answers
2k views

Create an equation using the following numbers and mathematical symbols: 4,2,1,2,4,+, =

Create an equation using only the following numbers and mathematical symbols: $$4,2,1,2,4,+,=$$
0
votes
0answers
56 views

A Dices Probability Riddle [duplicate]

Bob (A), Steven (B) and Joe (C) were playing with dices, each one of them made his own dice and wrote a number between 1-6 on each side of his dice. After playing for a while they've noticed that : (...
13
votes
6answers
2k views

Create integers using 1, 2, 3, 4, 5, 6, 7 and +, -

There are numbers $1, 2,3,4,5,6,7$ and signs '$+$' and '$-$'. Using only these numbers and signs, you can compose expressions and calculate the sum (difference). Concatenation operation is not valid. ...
4
votes
2answers
160 views

What is a Special Prime Number™?

This is inspired by the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles, now with numbers. If a number conforms to a special rule, I call it a Special ...
5
votes
2answers
496 views

What is a Chemical Number™?

This is inspired by the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles, now with numbers. If a number conforms to a special rule, I call it a Chemical ...
5
votes
5answers
224 views

May Make $\frac5{2020}$ 2020

For May 2020, try to create $\dfrac{5}{2020}$ using the least possible number of integers in the set $\{1,3,4,6,7,8,9\}$. $2$, $5$ and $0$ are not allowed. Example: $$\dfrac{4+1}{3\left(673+\frac13\...
11
votes
10answers
884 views

Four fours to get $\pi$ [closed]

Four fours is a famous puzzle (made trivial with logarithms). For this puzzle, we take inspiration from Glen O's challenge from a few years back. The rules here are slightly different, but the goal is ...
7
votes
2answers
1k views

Prime to number conversion

This puzzle relates to Prime to Prime: Get all first 25 Prime Numbers using up to 4 Primes and its sequel Prime to Prime Sequel Using any three of the first 4 prime numbers (2,3,5 and 7) and the ...
3
votes
1answer
122 views

Name that node #2

What is the value of the unknown node? Previous Name that node #1 (Beginner's Level Puzzle)
5
votes
1answer
124 views

Name that node #1 (Beginner's Level Puzzle)

While Puzzling.SE has some extremely clever and difficult puzzles that are being solved by people whose intellect amazes me, I wanted to make some graph puzzles that were specifically meant for ...
9
votes
0answers
415 views

I'm a number with a special product, so name me when you think you've got it

In the blocks that come before, their special product tells us more. To guess my scheme you'll need calculation, but only little tests of recreation. Each block contains atoms strong as Thor, ...
1
vote
1answer
308 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 ...
13
votes
9answers
4k views

How to get 32 by using +1 , +1 , ×3 , ×3 , ÷2 , ÷2, ^2, ^2?

How to get 32 by using +1,+1,×3,×3,÷2,÷2,^2,^2? (The last two operators are 'squaring'.)

1
2 3 4 5
8