Questions tagged [formation-of-numbers]

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

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5
votes
3answers
8k views

Make numbers 1-100 with only four 8s

Make numbers 1, 2, 3, 4, 5,.....100 using only four 8s. You can use multiplication, division, addition, and subtraction. No negatives. You may use exponents. Example: $1 = 8 \times 8 \div 8 \div 8$
9
votes
1answer
458 views

Arrange numbers into the quadrilaterals

Arrange numbers 1 to 14 to the quadrilaterals, such that: The difference between 2 numbers in squares having a common edge or corner is greater than 2. Numbers inside the green quadrilaterals are ...
6
votes
4answers
725 views

MS Excel Die Hard

You are John McLane, and Simon Gruber is back in town. This time he booby trapped 50 nuclear power plants across the US, and sent you a laptop he prepared, along with the following note: Any ...
12
votes
2answers
515 views

An omalonumerophobic's number sequence

Find all seven terms of the number sequence, a1, a2, a3, a4, a5, a6, a7 given that each successive term is exactly twice the value of the previous term no even digits are used in ...
14
votes
3answers
1k views

If 6 was 9, or 100 was 64, or M was N

         Now if a 6,          Turned out to be 9,          I don’&...
18
votes
1answer
571 views

Investment advice

I'm considering investing my money with a London broker who offers excellent returns. But the only information I can find about the investment are two numerical codes: Deposits: 3.428571428571......
-2
votes
1answer
29k views

Put the numbers 1, 2, 3, 4, 5, 6, 7, 8, and 9 so the total of each row, column and diagonal add up to the same number [duplicate]

Puzzle for grade 11 foundations of mathamatics course thank you in advance for the help
2
votes
5answers
695 views

Self reference is a pain [duplicate]

How many letters do the answer of this puzzle contain? NB: This came across while web surfing. I don't claim any ownership rights.
4
votes
7answers
327 views

Sum of three six digit numbers

This puzzle is a variation of a 3 digit addition puzzle I saw recently. A , B , and C are positive integers between 0 and 9. A,B and C are different integers Six digit numbers formed using A,B and ...
5
votes
3answers
1k views

Make numbers 1-100 using only the digits 2, 0, 0, 0?

I've already found several, the ones I mostly need are 13, 26, 34-40, and 64-85, but I figure it would be interesting to have a record here for other potentially easier/simpler methods.
5
votes
1answer
260 views

An EMIRP Game/ Puzzle for Prime enthusiasts

As most math enthusiasts know, EMIRPs are Prime Numbers which are also prime numbers when reversed. Like 17 which when reversed to 71 is also a prime number. Here is a Game or Puzzle based on 5 ...
9
votes
3answers
418 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   ...
0
votes
2answers
2k views

Arrange to get sum of 450 when it is added row wise and column wise

I just came across a maths puzzle,where i should get the sum of 9 numbers(multiples of 10) to be 450 both horizontally and vertically in a 9x9 matrix. Picture attached for reference:
-3
votes
3answers
355 views

If 71:64 then 92:? [closed]

This question was in the logical reasoning section of an exam I had recently appeared in. I still have no clue how this is solved. If 71:64 then 92:? The given options are- 25 32 35 ...
4
votes
2answers
523 views

Uncle's mathematics puzzles after dinner

I was at my grandmother's home for a dinner. With my siblings, after the dinner party, watching a prime time show. One of my uncles, who is a mathematics professor, didn't like and asked us to sit ...
1
vote
1answer
232 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 ...
9
votes
1answer
422 views

Prime to Prime change

Change the Prime Number 71549 to another Prime Number 10067 in Five steps by changing one digit at a time. Every time you change the digit the new number must be a Prime Number also. You cannot ...
-6
votes
1answer
2k views

Mathemetic series 1, 3, 6, 10, 15, 21, 28, 36, 45,__? [closed]

I currently looking what will be the next value to 45 as per given series. Is there any specific equation available?
3
votes
2answers
159 views

Complete the equality (medium-hard)

Complete the equality to make it true: 1 1 1 1 1 = 945 Using similar logic, solve for this: 1 1 1 1 1 = 80 Info: You should ...
3
votes
1answer
570 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 ...
-4
votes
1answer
147 views

Find relation between 2 numbers (username and password)

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 ...
13
votes
2answers
483 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? ...
2
votes
2answers
193 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 ...
11
votes
3answers
1k views

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 ...
18
votes
1answer
1k views

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, ...
5
votes
1answer
297 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 ...
7
votes
1answer
365 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 ...
19
votes
2answers
986 views

Self-intro to mo-Roman numerals

Here come mo -Roman numerals — just like Roman numerals, only mo’ so.   (Explained as we go.)   What number can spell itself in two different ways ...
4
votes
2answers
155 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 ...
-6
votes
4answers
205 views

Find 25 using 6, 25, 9, 8 only

You can only use these numbers once, so not square root or cubed root or anything else. Good Luck!!
4
votes
2answers
356 views

Arrange numbers 1 to 9 into the upsilon grid

Arrange numbers 1 to 9 into the octagon, so the operation is correct. C is a constant. Do the math operation in sequence, ($×$) and ($/$) is NOT HIGHER than ($+$) and ($-$).
9
votes
4answers
374 views

The pre-alpha calculator

You are given a rudimentary prototype of a calculator with only the following keys: 0 1 2 3 4 5 6 7 8 9 + - × ÷ = The display has place for 10 digits and is initially showing ...
8
votes
1answer
395 views

Arrange (+,-,x,/) into the upsilon grid

Put operators $(+,-,×,/)$ into the squares. Each operator must appears exactly 3 times to make the operations correct. C is a constant. No BODMA rules ((×) and (/) is NOT HIGHER than (+) and (−)), do ...
6
votes
7answers
865 views

Making 4 with 4 ones (with a twist!)

This puzzle is all about making 4 with 4 ones, but with certain constraints. Allowed operations: $-$ Subtraction $-a$ Negation $\times$ Multiplication $\div$ Division $\sqrt{a}$ Square Root $\sqrt[b]...
0
votes
2answers
173 views

Robbers - Make 24 [closed]

The make-24 puzzle is an oldie, but a very fun one at that. Given four different numbers, produce—through a sequence of operations upon only those four numbers—the number twenty-four. For example, ...
-1
votes
2answers
302 views

Coppers - Make 24 [closed]

The make-24 puzzle is an oldie, but a very fun one at that. Given four different numbers, produce—through a sequence of operations upon only those four numbers—the number twenty-four. For example, ...
37
votes
5answers
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 $\sqrt{a}$ ...
7
votes
4answers
2k views

A truly amazing way of making every possible positive integer

This is a follow-up to "A truly amazing way of making the number 2016": For every positive integer $n$, find a mathematical expression that yields the value $n$ while obeying the following rules:...
9
votes
7answers
49k 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 ...
33
votes
21answers
12k views

3:3! It's a football score! [closed]

Given to me, by a friend: How would you make 20, using two threes? You may use any basic operation. And others, such as square roots (the symbol), factorials, etc. Any operation is allowed. Just ...
15
votes
4answers
1k views

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 ...
4
votes
2answers
375 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
306 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 ...
26
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
700 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, ...