Questions tagged [formation-of-numbers]

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

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19
votes
17answers
10k views

Number 88 from the digits 2, 0, 1 and 7?

Can you use the digits 2, 0, 1 and 7 each only once to create the number 88?
3
votes
2answers
410 views

The Six Symbols

The professor turned to me and said, "I believe that all numbers in mathematics can be expressed with only 6 symbols." "A bold claim," I replied. "I suppose the you want all numbers to be encoded in ...
4
votes
1answer
391 views

Most consecutive positive integers using two 1s

Using two 1s, try to come up with the most consecutive positive integers. Allowed operations: Addition Subtraction Multiplication Division Concatenation Square Root Radical Factorial Floor and ...
5
votes
1answer
142 views

Tangled keyrings puzzle

Can you assign a unique number to all the keyring chains below and sort them accordingly? After you finished, can you think of arrangements that give some other numbers, different from the 15 cases ...
35
votes
6answers
8k views

Rendering the number 10,958 with the string 1 2 3 4 5 6 7 8 9

Brazilian mathematician Inder Taneja has found a way of expressing every number between 1 and 11,111, except 10,958, by inserting mathematical operators in between the numbers 1 2 3 4 5 6 7 8 9 and ...
10
votes
8answers
51k views

Make numbers 1 - 32 using the digits 2, 0, 1, 7

This is similar to the "Four fours" puzzle, but using the digits 2, 0, 1 and 7. Rules: Use all four digits exactly once Allowed operations: +, -, x, ÷, ! (factorial), exponentiation, square root ...
14
votes
5answers
17k views

10 9 8 7 6 5 4 3 2 1 = 2017

Add the four basic operators $\times\div+\,\;-$ and optionally brackets to: $10 \quad 9 \quad 8 \quad 7 \quad 6 \quad 5 \quad 4 \quad 3 \quad 2 \quad 1$ To get the total $2017$. Rules: Look for ...
4
votes
1answer
246 views

The Autonumerigram Challenge [duplicate]

Some phrases both refer to a number, n, and are comprised of n alphabetic characters. I call any such phrase an autonumerigram. For example, four has 4 letters seven plus seven has 14 letters ...
12
votes
3answers
732 views

Self-Factorial Number

Self-factorial number is the number where its digits' factorials summation is equal to the number itself. But there are only a few amount of them. For example; $1=1!$ $2=2!$ $145= 1!+4!+5!$ So ...
27
votes
9answers
8k views

A clock for 2017

Design a clock where each number from 1 to 12 is obtained as an arithmetical operation using each digit of 2017 exactly once: for example, 4 could be made as $2\times 7-10$.
3
votes
5answers
4k views

Minimum difference with Digits

You have digits from $0$ to $9$, where you have to use every digit only once. create 2 numbers from the digits so the difference is minimum. example : $30568 - 29471 = 1097$ What is the lowest ...
8
votes
2answers
634 views

Maximum Result with Digits

You have digits from $0$ to $9$, where you need to use every digit only once, and you have only one operator (multiplication, $*$). You may combine/join digits to create a bigger number as shown below:...
3
votes
2answers
163 views

Arrange numbers to the equations, so if we turn the equations upside down, they are still right

_ + _ = _ _ + _ = _ _ + _ = _ _ + _ = _ Fill the blanks with numbers above, so: The 4 additions are right. All numbers must be used. If we turn the additions upside down, they are still right, ...
-3
votes
2answers
211 views

Find the correct sign

This is a question in a primary school book as a riddle. How can we put any mathematical sign (addition , subtraction, multiply and division) between five 5s to get the answer 66? 5 5 5 5 5=66
-5
votes
1answer
207 views

3 is the magic number [closed]

I am wondering what is the answer to these if the magic number is 3. So like.. 1 1 1=3 2 2 2=3 3 3 3=3 4 4 4=3 5 5 5=3 6 6 6=3 7 7 7=3 8 8 8=3 9 9 9=3 10 10 10=3
4
votes
1answer
184 views

Numbers at a flower-like circles

Above picture is a flower-like circles with digits to each intersection which follow the rules: A circle and its center must contain all of the digits from 1 to 7. I have put some numbers to some ...
4
votes
1answer
519 views

Arrange numbers and operators to the magic triangle

Note : A # B = A*10 + B Arrange the numbers 1 to 9 to green triangles, and arrange operator (+,-,x,/,^, and #) to the white triangles, so the math operations below are equals. (((A op1 B) op2 D) op3 ...
4
votes
3answers
414 views

Arrange numbers to a 6 point star

Arrange the numbers (1,2,3,4,5,6,7,8,9,11,12, and 16) to replace the letters, so every 3 vertices which form a triangle have equal sums.
5
votes
1answer
159 views

Arrange numbers and operators to piano-keys

Let a # b = a*10 + b Example : 5 # 5 = 55 9.5 # 3 = 98 Arrange numbers 1 to 7 to each piano's-white-keys. Then arrange operators (+,-,x,/, and #) to each ...
5
votes
4answers
664 views

All digits with one operation

I can't find this very easy, simple puzzle here, so here goes: Using all ten digits from 0 to 9 exactly one time, find an equation (using =, not !=, don't be silly) that uses only one of the ...
5
votes
3answers
916 views

Ane and her block toys

Ane is a very smart kid. She has 9 number blocks [1] to [9], and 2 operation block [+] and [x]. Today She is playing with her blocks. She is so happy after arranging her blocks, then perform the math ...
8
votes
2answers
3k views

Can you solve the 7x7 (sudoku-ish) centered sums puzzle

I have come across this puzzle a few times in competitions and rally's, and it has troubled me because I cannot seem to find a good approach to solving it, either programmatically or numerically. And ...
5
votes
4answers
419 views

Numbers at the corners of concentric squares (part 2)

Put 4 distinct 1-digit non-negative numbers (A, B, C, D) on every vertex of a rectangle. Then put the last digit of the product of 2 connected vertices at the sides of the rectangle. Create a ...
3
votes
4answers
366 views

Numbers at the corners of concentric squares

Put 4 distinct 1 digit non-negative numbers (A, B, C, D) to every vertex of a rectangle. Then put the last digit of the sum of 2 connected vertexes at the sides of the rectangle. Create smaller ...
14
votes
1answer
359 views

Presti-digit-ation

In the spirit of lightweight prestidigitation, take a break to enjoy a gimmicky digital magic show. .'''''''''.---> _________________________ An ordinary 4-digit decimal : 3 9 1 8 :--->...
17
votes
6answers
1k views

Unique representation ID for 5-card poker hand using combination without sorting

There is a deck of 52 playing cards (e.g. poker cards). Assign every card a unique number (ID) at will. Every combination of 5 of these cards (a "hand") shall be represented by a unique result number, ...
4
votes
1answer
1k views

Arrange the numbers 1 to 19 in the circles

O---o---O / \ / \ o o o o / \ / \ O---o---O---o---O \ / \ / o o o o \ / \ / O---o---O Arrange ...
5
votes
8answers
8k views

5008 out of the box

So I came across this puzzle somewhere: And the intended answer to it was: But that's pretty much straight forward. Thinking out of the box you can get a lot bigger "numbers" (values), for example: ...
1
vote
9answers
389 views

Use numbers 1-9 to yield 300000

Inspired by @Saiid's earlier question. Using $+,-,×,÷,$ exponents and factorials, use all the numbers $1-9$ (once and only once each) to generate $300 000$. Don't compose numbers from their digits, ...
1
vote
2answers
2k views

$7777/6666 = -212$

The title explains it pretty much, make $7777/6666$ equal $-212$. The following operators can be used. $+,-,*,/,\hat{},()$ Rules: Each number can only be used once You can move the numbers around ...
6
votes
18answers
5k views

Use the numbers 1-9 to equal 1150 [closed]

Not sure if this is too hard, but it's a more or less simple math puzzle. Use the numbers $1,2,3,4,5,6,7,8,9$ to get an answer of 1150. You can use the operators $+,-,*,/,\hat{}$ You can use ...
6
votes
4answers
752 views

(addition) 7 point star / heptagram

Place the numbers $1$ through $14$ onto each point, so that: A = 1 The sum of points in every line are equal, (A+I+J+C = B+J+K+D = C+K+L+E = D+L+M+F = E+M+N+G = F+N+H+A = G+H+I+B) A+B+C+D+E+F+G+1 = H+...
0
votes
10answers
1k views

Get 6 6 6 6 to equal 58 [closed]

$6 6 6 6 = 58$ $+ - * /$ and $()$ only 58 must remain as 58, (not 5 + 8, etc.)
3
votes
2answers
3k views

Finding the largest 7-digit number

Find the largest 7-digit number without its digits repeating, such that the number is divisible by all of its digits I found some constraints: • 0,4 and 5 cannot be included • The number found should ...
3
votes
2answers
305 views

Find a Strobogrammatic number, so if we square it, the result is a pandigit number

Find a Strobogrammatic number, so if we square it, the result is a pandigit number. Note : A Strobogrammatic number is a number when typed on a calculator, and the calculator is spun 180 degrees, ...
3
votes
1answer
521 views

Find the rule : triplet number into Positive Integer

These are triplets of numbers into positive integers: ...
5
votes
4answers
1k views

Making 1-50 from 2016

Make the numbers 1-50 using the numbers 2 0 1 6 in the given order. 1.You must use all four digits. 2.You may not use any other numbers. 3.You may use +, -, x, ÷, square root, squaring and cubing, ...
41
votes
16answers
5k views

What is the smallest set of letters that can spell any integer? [closed]

Today my 9-year-old nephew told me that he can spell any integer in English using only 9 letters. This is how he's doing it: ...
1
vote
2answers
248 views

modified 3x3 panmagic squares

This is a modified 3x3 panmagic squares. The square is divided into 2 triangles. Numbers 1 to 9 is arranged to upper triangles. Numbers 10 to 18 is arranged to lower triangles. All rows, all columns, ...
5
votes
1answer
639 views

Check digit number : Find the maximum number of distinct ways

Find the maximum number of elements in a set containing combinations of three digits (from 0 through 9) with the following rules: Each digit can be used more than once. Any two combinations in the ...
4
votes
2answers
316 views

The mathy square strikes back!

This is a follow-up question to Does this mathy square have any solutions? (And how many?). Consider a 7x7 grid of math operators o and numbers ...
13
votes
4answers
1k views

Does this mathy square have any solutions? (And how many?)

Consider a $5\times5$ grid of math operators and numbers that encodes 8 math equations: A + B = C = + + + + D + E = F + = = = = G = H + I There are 3 horizontal ...
-2
votes
3answers
697 views

Can you express 1844 in a curious way? [closed]

Can you find integer values for $p$ and $q$ with $p,q\in\{0,1,2,\ldots,9\}$ so that the following equation holds? $p^q - q^p = 1844$
5
votes
2answers
521 views

Reveal all five equations

Five men enter a bar. 1st man order 1 Pepsi and 1 Cocacola 2nd man order 2 Pepsi and 1 Cocacola 3rd man order 3 Pepsi and 1 Cocacola 4th man order 4 Pepsi and 1 Cocacola 5th man order 5 Pepsi and ...
2
votes
2answers
339 views

It is related to a type of mathematics game

Start with two digits from $1\dots9$ to form a $2$-digit number. Multiply this number by a single digit from $1\dots9$. Add the result to another two digit number from $1\dots9$, and calculate the ...
5
votes
1answer
2k views

Expressing numbers using 0, 1, 2, 3, and 4

The least number that cannot be written using the numbers 0, 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
3answers
358 views

Number wheel Challenge!

Much like the Word-tank-wheel challenge, but numbers! Find a number that can 'rotate' in a way that the origin number and its rotations must be divisible (i.e. whole number) by the number of times it ...
5
votes
4answers
526 views

Find the next number in the sequence [closed]

One tough puzzle to solve : Find the next number in the sequence : 5,105,74,712,37,? Options are : a. 2008 b. 57 c. 507 d. 98 e. 44 What is the next number, and why? Puzzle ...
13
votes
2answers
624 views

Help me find my friend!

I need your help! My friend has gone missing and I have no clue where he could be! However, he did manage to get a message out to me: Kidnapped. Send help. I am here: port town. $\left\lfloor\sqrt{\...
10
votes
3answers
1k views

Two functions that can't be applied in different order to arrive at same result

Here's my puzzle: Write two unary functions f, g and provide an input x so that only the ...

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