# Questions tagged [formation-of-numbers]

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

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### Find the ? in this grid

Find question mark in this grid with numbers. csv version: 9,6,7,3 2,4,7,6 4,1,5,8 3,0,3,? Hint: You use all numbers to find ? and it is much more simple ...
614 views

### What's the largest number that can be obtained in the process of solving a numbers game on Countdown?

Countdown is a British game show in which people try and make the longest possible word out of nine given letters, reach a target number using six given numbers and basic arithmetic, and then solve a ...
165 views

### Draw out a Battle!

I'm thinking of a number. It's 5 digits long There's a 5 between a 7 and a 2. The second-biggest number is on the far right. The average digit value is equal to the second-lowest digit. The smallest ...
986 views

### Make 12 with 1, 5, 19, 10

How can you make the number 12 with just the numbers 1,5,19,10? You can only use each number once, and can only use subtraction addition multiplication and division.
2k views

### Fill in the operators to make $7 \circ 8 \circ 7 \circ 7 \circ 8 \circ 3 = 100$

With the given numbers I need to make: $7 \circ 8 \circ 7 \circ 7 \circ 8 \circ 3 = 100$ Using only the following operators: $+\space-\space\times\space\div$
279 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, ...
923 views

### Mathematical riddle [duplicate]

Part one: You are presented with ten incomplete equations: 0 0 0 = 6 1 1 1 = 6 2 2 2 = 6 3 3 3 = 6 4 4 4 = 6 5 5 5 = 6 6 6 6 = 6 7 7 7 = 6 8 8 8 = 6 9 9 9 = 6 Your job is to fill in mathematical ...
2k views

### My colleague gave me a number puzzle

My colleague probably has left work now, he is no longer responding. He gave me this puzzle and asked me to fill in the '?': ...
544 views

### Find the smallest positive integer that cannot be made from four 8s, or show it doesn't exist

This puzzle was inspired by one recently posted by @Max. What is the smallest positive integer that cannot be made from four 8s, where bracketing is allowed and the only permitted operations are ...
472 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 ...
734 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 attempt ...
547 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 ...
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’&...
572 views

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......
42k 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
701 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.
348 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 ...
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.
274 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 ...
445 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   ...
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:
359 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 ...
573 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 ...
257 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 ...
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 ...
3k 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?
164 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 ...
594 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 think the answer is:
155 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 ...
539 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? ...
194 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 ...
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 ...
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, ...
303 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? [?]     B- What is ...
401 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 ...
1k 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 ...
190 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 ...
211 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!!
384 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 ($-$).
389 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 ...
400 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 ...
894 views

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 ...
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 ...