Questions tagged [formation-of-numbers]

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

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70
votes
15answers
13k views

Making π from 1 2 3 4 5 6 7 8 9

There have been two other questions here and here that are similar to this one, but this changes the rules up a little. Your job is to approximate $\pi$ using the sequence of digits (in order): 1 2 ...
-3
votes
0answers
136 views

What is wrong about the following code?

A colleague asked me this question What is wrong about the following code: ...
5
votes
2answers
1k views

Euler's identity

Warning: this question requires knowledge of complex numbers. An Euler's identity is an identity, in which each of the following appears once and only once: the constant $0$: neutral element for ...
-4
votes
1answer
100 views

How do I solve this puzzle?

I am trying to answer this puzzle - which of the five potential answers is correct, and why? This test comes from Metropol iq1 book
0
votes
2answers
100 views

How do I solve this numerical puzzle?

I am trying to answer this numerical puzzle - which of the five potential answers is correct, and why? 6*3*5 = 183033 5*4*3 = 201532 7*2*7 = 144928 8*2*9 = ? ...
4
votes
1answer
2k views

I want an exact value of Pi

Use 1, 2, 2, 2 (Each number used exactly once) to form π. I want an exact value of π, not any approximation. Available operators: + - * / ( ) ^ ! You can use any one of them for any times. Hint:...
7
votes
4answers
582 views

How to make the number 49?

You've to start with $1$ and can use each of the following operations at most once. You can do the following in any order you like: 1) Add $2$. 2) Add $3$. 3) Add $5$. 4) Multiply $2.$ 5) ...
-3
votes
2answers
223 views

What is the next number in the sequence and why?

7 4 11 2 14 5 18 3 21 ? Find the next number in the sequence?
3
votes
2answers
192 views

SAME DIGIT NUMBER PUZZLE

You have 5 numbers 1, 9, 3, 5, and 7 you need to arrange these number like Rules create 2 pairs from numbers above keep one of the number in the middle then apply this law ...
6
votes
3answers
640 views

Number Equation Matrix

Can somebody please solve this? My daughter's school teacher gave her this puzzle to solve at home. But to me it seems a little out of order, and that's why I am asking here for help.
1
vote
1answer
92 views

Find the missing number (number sequence puzzle) [duplicate]

Find the missing number 56784 = 4 11111 = 0 72348 = 3 88652 = 5 88811 = 6 75213 = 0 65465 = 3 62257 = ? I found this quiz in an archive of our company's ...
1
vote
3answers
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 ...
12
votes
16answers
5k views

Make 2019 with single digits

This puzzle is inspired by a puzzle by @Andrew, where the goal is to make 1998 from a minimal amount of 8s. This is a variation of the puzzle, where the goal is to make 2019 using a minimal amount of ...
-3
votes
2answers
128 views

How do you make 29 only using the numbers 1 2 3 4 [closed]

How do you make 29 with only using the numbers 1 2 3 4? I have tried a lot of solutions and please remember that you can't use the number 5
44
votes
10answers
148k views

1 2 3 4 5 6 7 8 9 = 100

The sequence of numbers $1\ 2\ 3\ 4\ 5\ 6\ 7\ 8\ 9$ has the property that you can insert mathematical operators in between the numbers from $1$ to $9$ and make the expression evaluate to 100. For ...
32
votes
18answers
11k views

Use 2, 0, 1 and 8 to make 109

Assemble a formula using the numbers $2$, $0$, $1$, and $8$ in any order that equals 109. You may use the operations $x + y$, $x - y$, $x \times y$, $x \div y$, $x!$, $\sqrt{x}$, $\sqrt[\leftroot{-2}\...
62
votes
24answers
20k views

Make 0 0 0 0 = 8

Can you find a way to make: $0\ 0 \ 0 \ 0 = 8$ by adding any operations or symbols? You can use only these symbols: $+,\ -,\ *,\ !,\ /,\ \hat\, ,\ ()$. It is limited to this list, and ...
21
votes
12answers
5k views

Make 1998 using the least possible digits 8

Make the number 1998 using the minimum amount of digits 8. Your allowed operations are +, -, *, /, ^, % (percent). You need not use only integers 8: 88 and the likes are acceptable. You must only ...
5
votes
4answers
195 views

Find 2018 with the least amount of numbers

Can you assemble a formula using the least amount of one digit numbers (from $0$ to $9$) so that the results equals to 2018 with the rules below? You may use the operations $x + y$, $x - y$, $x \...
14
votes
4answers
1k views

Squares inside a square

Distribute the digits from 1 to 9 to a 3x3 square, such that you reach as many square numbers as possible. A valid square number in the 3x3 square is either a single digit square number or is build ...
4
votes
1answer
206 views

Find pattern for new equation in number sequence

I saw this puzzle on this address. $3+5+7=152181$ $4+5+6=202461$ $3+4+7=122172$ $9+4+5=364518$ $8+6+8=?$ I know that first $4$ digits are $4864$. How could I find last $2$ ...
10
votes
1answer
177 views

Make $2471$ out of first seven powers of two

Can you make $2471$ using first seven powers of two: $1,2,4,8,16,32,64$, each exactly once? Only the basic operations are allowed: $+,-,\times,\div$, and parentheses $(\space)$. ...
14
votes
3answers
1k views

How many consecutive integers can you make using only four digits?

In the spirit of the classic four fours, I wonder what's the optimal set of four numbers? Your goal is to make the most consecutive integers using four digits of your choice. Pick four: $0,1,2,3,...
12
votes
6answers
724 views

Use 0 1 2 3 4 to form 9 3-digit numbers

Use $0, 1, 2, 3, 4$ to make the any of these numbers: $$331, 333, 435, 452, 455, 458, 461, 469, 470$$ You must use all $5$ digits $0, 1, 2, 3, 4$ each exactly once. You can make multi-digit ...
8
votes
3answers
5k views

How to make 21?

How do you make $21$ from the numbers $1$, $5$, $6$, and $7$? You can use the operations of addition, subtraction, multiplication and division, as well as brackets. You must use each number exactly ...
6
votes
1answer
169 views

How to make the two important years 1492 and 1969 with a minimum number of 1s

Using only 1s, make 1492 and 1969 with the minimum number of digits Rules: allowed operations +, -, ×, ÷, ^, (), and ! (factorial). Concatenation of the original digits is allowed, but not (1+1)1=21. ...
2
votes
10answers
15k views

Make numbers 1-30 using 2, 0, 1, 9

This is very similar to the 2, 0, 1, 8 problem. Just try to make all numbers 1-30 using the digits 2, 0, 1, 9. Rules: Use all four digits exactly once Allowed operations: +, -, x, ÷, ! (factorial), ...
7
votes
1answer
178 views

How do you make 66 using three 4s

Rule: allowed operations: +, −, ×,/,^,√, and ! (factorial) example: 4^4+4!=280
11
votes
6answers
2k views

Some interesting calculation puzzle that I made

So I'm creating some kind math puzzle that goes like this: 1=-2+3 12=3*4 123=(4*5)+(6+7)*8-9+10 (thanks JS1 for finding shorter one) 1234=(5*6*7*8)-(9+10+11+12+13+14+15+16+(17*18)+19+20+(-21+22)) ...
2
votes
3answers
193 views

IQ test sample patterns. Can anyone find the missing number? [closed]

I am fully hopeful that you can crack this puzzle. You need to answer with an explanation.
4
votes
3answers
231 views

Use digits 3 3 5 to make 67 or 97

Rules: All 3 digits — $3$, $3$, and $5$ — must be used once each in any order. You can concatenate these digits to create multi-digit numbers (i.e. $33$). You can use the factorial ...
0
votes
1answer
81 views

Puzzle on a blackboard [closed]

What is the missing number in the picture above?(question is from some puzzle game) I tried some approaches, but haven't found any meaningful rule..thanks in advance!
19
votes
17answers
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?
8
votes
1answer
237 views

Riddle to Code 2: The return of numbers

The first is a pirates favorite letter. The second is from a famous quote of shakespear. The third is squaring it off in a famous formula. The fourth is the first in a very well known song. ...
11
votes
4answers
4k views

Use 1 9 6 2 in this order to make 75

I'm looking for a solution to make number $75$ with numbers $1$ $9$ $6$ $2$ in that order and the same rules as in Use 2 0 1 and 8 to make 67. Here a copy of those rules: You must use all 4 digits. ...
15
votes
7answers
9k views

Make 24 using exactly three 3s

Make 24 using exactly three 3s Each number formed with a 3 and the 24 in the equation are all base 10. You cannot introduce any additional digits or constants. Plus(+), negation/subtraction (-), ...
23
votes
2answers
513 views

The mysterious operation $\oplus$

We are given an operation $\oplus$ that is associative and commutative, has $0$ as a neutral element, and we know: $1/10 \oplus 1/6 = 5/29$ $1/6 \oplus 2/3 = 7/10 $ $1/5 \oplus 2/5 = 3/7 $ $1/4 \...
7
votes
1answer
205 views

Make a formula to get the highest score

In this puzzle you need to obtain the highest score with the following rules 1) choose two digits from 1, 2, 3, 4, 5, 6, 7, 8 and 9. These digits are represented by two letters, let us say $T$ and $M$...
8
votes
2answers
571 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:...
14
votes
3answers
627 views

Hiker's Cabin Mystery | Pt. II

See Part I | See Part III Nice one, @GarethMcCaughan! Finally, you've gotten into his computer using the password you managed to decode from his clues... but there's another issue! There is a ...
27
votes
4answers
35k views

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 ...
0
votes
1answer
132 views

He said yes..she said no..they went back and forth..they agreed to [closed]

To call it a Prime. S, N, O are 3 distinct digits that are to be determined by you so that their conclusion is right Full concatenated number: SNOSNOS
-4
votes
10answers
936 views

SafeCracker #3 - We've Been Blocked [closed]

Our Last Safe To Conquer Ok, team, this one might give us a little trouble. Nothing we can't handle though... let's go... This safe model is "The NevaCrak 9000" - the most secure safe there is. ...
12
votes
11answers
18k views

Combine 3, 3, 5 & 7 to get 24

Using operators plus, minus, multiplied by and divide by, and as many brackets as you want, can you do a formula which uses 3, 3, 5 and 7 to make 24? Each number must be used and can only be used ...
1
vote
2answers
337 views

The result is 7 game

The goal of this game is to find the lowest score for the 10 equations below. 0 ? 0 ? 0 ?...
28
votes
9answers
5k views

How many consecutive positive integers can you make using exactly four instances of the digit '4'?

Starting at 1 (which is 4 - $\sqrt4$ - 4/4), how many consecutive integers can you make using exactly four instances of the digit '4'? Basic rules: Any operator symbol is "free". Any printed '4' ...
3
votes
1answer
121 views

some sequences are awesome!

My name is Awesom$\Sigma$ Sequenc$\Sigma$. Nice to meet you all :). I am new here. You can either use my first name or last name to address me. My hobbies include visiting new places. I usually ...
26
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 $2\times 7-10$.
14
votes
2answers
419 views

Construct $\sqrt{3}$ using every natural number

Construct $\sqrt{3}$ using every natural number $n\in \mathbb{N}$ (1, 2, 3, 4...) exactly once and the operations addition ($+$) and division ($\div$).
8
votes
1answer
257 views

A Number Game puzzle

Our team has created 9 math puzzles with ranging difficulty. Let me share one of them. At the beginning a number is given to you. Your objective is to get a different number by making choices. Here's ...