Questions tagged [formation-of-numbers]
For puzzles about forming numbers using other numbers and mathematical operations. Use with [mathematics]
360
questions
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 ...
asked Jan 12 '17 at 21:57
Bernardo Recamán Santos
12.9k2 gold badges23 silver badges116 bronze badges
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 ...
asked Aug 9 '16 at 13:06
Bernardo Recamán Santos
12.9k2 gold badges23 silver badges116 bronze badges
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 ...
