# Questions tagged [formation-of-numbers]

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

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### Integers around a circle with consecutive pairs adding to a square

The integers 1 to 50 are placed around a circle in such a way that the sum of any two of them which are adjacent is a perfect square. Of these integers, the even numbers are then removed. Restore them....
2k views

### How can you get 125 from 2,3,4,5,6?

You are allowed to use the four standard operations (+-/*) to get 125, using each of the following digits exactly once: 2, 3, 4, 5, and 6. I came up with an answer, but took me a while; curious to ...
324 views

### 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 ...
2k views

### Make 38, 44, 46 using 2,3,8,7?

Using BODMAS/BIDMAS* and the numbers and signs 2,3,7,8, (), -,+,÷,× can you make 38, 44, 46. You can only use each number once. I can't figure it out myself Brackets Order Division Multiply Add ...
153 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 ...
792 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 '?': ...
364 views

### Number sequence with two missing numbers 15, 39, 1/8, 1/49, 100, 11, _, _

Given the following incomplete number sequence: 15, 39, 1/8, 1/49, 100, 11, __, __ What are the two missing values?
513 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 ...
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: $1 = 8 \times 8 \div 8 \div 8$
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 ...
726 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 ...
518 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 ...
31k 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
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......
696 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.
328 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.
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:
357 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 ...
263 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 ...
562 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 ...
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 ...