Questions tagged [formation-of-numbers]

For puzzles about forming numbers using other numbers and mathematical operations.

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11
votes
4answers
404 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
3answers
444 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
167 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
625 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
87 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
109 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
102 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!? ...
6
votes
4answers
641 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
133 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
70 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 ...
6
votes
0answers
156 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
142 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
116 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
162 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
276 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
297 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
148 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
164 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
431 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
695 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
149 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
252 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
8answers
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
55 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
1k 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
133 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
488 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 ...
4
votes
5answers
203 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
782 views

Four fours to get $\pi$

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
121 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
120 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 ...
8
votes
0answers
377 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
210 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 ...
14
votes
8answers
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'.)
2
votes
2answers
190 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 ...
6
votes
1answer
124 views

A Tribute to Countdown [closed]

Leave empty or put a multiplier, divider, adder or subtractor in the boxes: For example:
-2
votes
2answers
327 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. ...
14
votes
2answers
666 views

Shots, shots, shots, shots!

Once in a while I go out for a drink to my favourite bar. Normally is just drink a beer, eat some snacks and have a good time with my three friends. But last night I wanted to do some shots. The ...
5
votes
1answer
385 views

Building number 81 with 1,3,3,5

You are given the numbers 1,3,3,5. Use any operation of +,−,∗,/,() to build 81 with those four numbers. You must use all four numbers exactly once. No concatenation, exponential or other symbols like ...
2
votes
6answers
611 views

Make expressions equal to 4 using exactly three 7s

Use exactly three 7s in every expression and no other digits/numbers. Choose from among addition, subtraction, division, and/or multiplication operations. You may use parentheses, brackets, and/or ...
9
votes
4answers
2k views

Four $\pi$'s to make any integer

This is like the "four four's" puzzle. The challenge is to represent any integer using $\pi$,$\pi$,$\pi$,$\pi$ (uses $\pi$ exactly $4$ times). You can use common functions on a calculator: Normal ...
7
votes
5answers
1k views

9 8 7 6 5 4 3 2 1 = 0 and 1 2 3 4 5 6 7 8 9 = 0

There are many number sequence puzzles on this site. I acknowledge them all. Martin Gardner introduced the puzzle with the 9 digit sequence with math operations, reaching 100 as below An old ...
14
votes
4answers
2k views

Emoji primes - what's the smallest positive integer this doesn't work for?

Driven by a silly conversation at work, here's the puzzle. Slack allows users to send emoji as a reaction to a message. Emoji are listed left to right in chronological order of reaction, and 'stacks' ...
14
votes
6answers
3k views

Make expressions equal to 100 using exactly seven 4s

Use exactly seven 4s in every expression and no other digits/numbers. Choose from among addition, subtraction, division, and/or multiplication operations. You may use parentheses, brackets, and/or ...
-3
votes
1answer
186 views

Make 100 with only 9 numbers [closed]

Make 100 with ONLY 9 numbers Hint 1: Hint 2: Hint 3: Hint 4:

1
2 3 4 5
8