# Questions tagged [formation-of-numbers]

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

235 questions
538 views

### Can you find the pattern?

If the following are true: $4+7+2 = 281435$ $7+3+9 = 212781$ $6+2+7 = 121456$ $2+8+5 = 164036$ Then what would the following equal? $8+4+6\ =\ ?$ Can anybody check my work? I ...
144 views

I have a two sets of Usernames and passwords as follows: User --> Password 1456 --> 3473 1360 --> 3377 Now I have to find the password for 1301. Could anyone please help find the relation (it is ...
219 views

### Shortest path from one $\to$ ten with a twist - Updated

NOTE: The rules have been updated to cause the nature of the puzzle to be as intended. I will upvote the answer which was given before the change, but I look for both alphabetic and math operations to ...
6k views

### Make 10 out of 1, 1, 5 and 8

A friend of mine shared a puzzle with me this evening. Using the numbers 1, 1, 5 and 8 exactly once, and the basic operations (+, -, /, *) and (optionally) parentheses, form an expression which ...
173 views

### Hexadecimal = n times decimal

Was explaining hexadecimal numbers to a friend and this made me wonder: "Is there an hexadecimal number x that is a whole number n times its decimal value ?" So for example the hexadecimal number ...
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### How to get 5 from 0,0,0 and 1?

Can you use the digits 0,0,0 and 1 each only once in a mathematical expression for the number 5 using only common mathematical symbols with at least 1 mathematical symbol between each number?
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### Find the correct math words to equals the intended number

I am testing a new puzzle. I hope the puzzles are intersting. Example: 3 7 7 2 4 = 40 Answer: two(3) hundred(7) divided(7) by(2) five(4) = 40 Rules: Find the correct words. Numbers of letters have ...
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### If 6 was 9, or 100 was 64, or M was N

Now if a 6,          Turned out to be 9,          I don’&...
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### New Mathematics forever

This has been (renamed and) refocused on boboquack’s unforeseen solution, which deserves its own puzzle. Right when you thought the good old days of New Mathematics were safely dusted, ...
281 views

### Sticking Numbers

Try to figure out the answers from the 2 patterns below. Find all the 10 digits first. Rotate if necessary. A: What is the missing number? [?] [10] [11] [9] [11] B- What is ...
296 views

### Arrange numbers to the triangles, so the sums are equal to S

Rules: Arrange numbers from 1 to 11, and each number can appear max twice. The numbers are arranged, so that any 3 numbers which forming an up-triangle sum to the desired number (S). A equal sign ...
130 views

### Representation of Mo-roman numerals

This continues the spirit of Mo-roman numerals started by humn What is/are the natural number(s) that has/have the most different representations in mo-Roman numerals and what is the number of ...
461 views

### A mo-Roman sampler

Pluck some relatively easy mo-Roman mini-puzzles while there’s relatively easy pickin’s. What two English words, taken as mo-Roman numerals, form the same number? ...
838 views

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### Create all numbers from 0-100 only using all of 1,2,3,4 and 5

Create all numbers from 0-100 only using 1,2,3,4 and 5. No repeats and you have to use each number. Also, you can use any operation. I've only gotten to 50 by pure brute force. I think that this might ...
6k views

### Making 103 from 4 zeroes

As the title suggests, the puzzle here is making the number 103 by using exactly four 0s and the following operations: $+$ Addition $-$ Subtraction $\times$ Multiplication $\div$ Division $\sqrt{a}$ ...
393 views

### Sum self enumerated digits

Please fill in the entire summations for lines 4 through 9 and just the total for line 1,000,000.         1.     1   =   1   ...
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### February 2017 golf

How many minutes are there in February 2017? This is "puzzling golf". The shortest correct answer wins. PS: The puzzle is not so much to compute the result, but rather to express it in fewer than 5 ...
9k 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?
367 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 ...
281 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 ...
135 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
229 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 ...
676 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 ...
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### 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 $2*7-10$.
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### 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 ...
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### 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:...
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, ...
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
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### 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
148 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 ...
346 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 ...
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### 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.
147 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 ...
652 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 ...