Questions tagged [formation-of-numbers]

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

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3
votes
2answers
380 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 ...
2
votes
1answer
307 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 ...
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, ...
5
votes
1answer
136 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 ...
27
votes
11answers
6k views

Make 11 from five identical digits

At a tender age my father introduced me to an arithmetic game: making the number 11 from five single digits using only the basic operators listed here: ...
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
235 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
704 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 ...
3
votes
2answers
160 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
208 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
186 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
158 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
456 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
365 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
157 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 ...
8
votes
2answers
2k 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
3answers
911 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 ...
5
votes
4answers
660 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
4answers
403 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 ...
12
votes
1answer
331 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 :--->...
3
votes
4answers
357 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 ...
4
votes
1answer
835 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
3k 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: ...
4
votes
1answer
277 views

Create a 3x3 table with a specific rule

Take 9 distinct numbers from [0 to 9], then put the numbers to a 3x3 table, so : Each cell = Last digit of (sum of 2 numbers in the same row of the cell + sum of 2 numbers in the same column of the ...
1
vote
9answers
376 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, ...
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 ...
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 ...
-2
votes
5answers
539 views

Form a number using some numbers and mathematical operations

Using 2,3,4,5,6,7 and basic mathematical operations form the number 1088. Every digit must be used exactly once (neither zero nor greater than one times). Concatenation of digits (such as 53) is not ...
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
2k 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 ...
2
votes
2answers
332 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 ...
3
votes
1answer
511 views

Find the rule : triplet number into Positive Integer

These are triplets of numbers into positive integers: ...
40
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: ...
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, ...
1
vote
2answers
223 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
510 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
296 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 ...
14
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
518 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 ...
4
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
320 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 ...
6
votes
4answers
512 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 ...
12
votes
8answers
2k views

Make 1 with any 3 of the same numbers

Is it possible to make 1 with any 3 numbers, all the same, such as using 3, 3 and 3 or 6, 6 and 6? Can you think of a proof which will work no matter which number it is? Trig functions allowed.
13
votes
2answers
599 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\...
-5
votes
4answers
442 views

A Wonderfully Tricky way of Making any Positive Integer [closed]

Make all positive integers, starting from $1$, using: Exactly four $4$'s (and no other digit), concatenation being allowed, Any standard mathematical symbol(s) and operation(s) not listed below. ...
-5
votes
3answers
1k views

Make 82 With Numbers and Dots

How do you make 82 with the numbers $4, 5, 6, 7, 8, 9, 0$ and 8 dots. Get creative! You can use any mathematical operation, and the dots can be used in any mathematical way. No ratios. You must ...
-5
votes
2answers
1k views

Make 24 and 30 using the digits 3 and 4

First, write an expression using exactly one 3 and exactly one 4 to make 24. Second, write an expression using exactly one 3 and exactly one 4 to make 30. Math You Can Use for each problem: ...
1
vote
1answer
413 views

Riddle with functions [duplicate]

The following is a riddle, that is not so easy as it seems. Using the numbers 1, 3, 4, 6 only once, you must use any of the functions (addition, multiplication, division, subtraction) in order to form ...
11
votes
2answers
329 views

Make a certain number with an unusual calculator

The Kasio Kool-Kalk™ is a poorly-designed calculator with only two buttons, labelled $[A]$ and $[B]$. Pushing $[A]$ replaces the currently displayed number $x$ with $2-\frac{1}{x}$. Pushing $[B]$ ...