Questions tagged [formation-of-numbers]

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

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-3
votes
0answers
133 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
578 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
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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
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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
639 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 ...
-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
12
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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 ...
21
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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 ...
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 $(\space)$. ...
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. ...
7
votes
1answer
178 views

How do you make 66 using three 4s

Rule: allowed operations: +, −, ×,/,^,√, and ! (factorial) example: 4^4+4!=280
11
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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
191 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
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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
80 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!
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. ...
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 ...
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. ...
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 $M$...
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 \...
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 (-), ...
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
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 ...
-4
votes
10answers
934 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. ...
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 ...
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 ?...
14
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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 ...
4
votes
2answers
448 views

How to make 18 from 1, 3, 4, 8

This question was on my sister's 5th-grade homework, practicing order of operations. It was to make 18, using the numbers 1, 3, 4, 8 and the operations +, -, and *. The instructions imply using each ...
6
votes
2answers
231 views

For what x can we solve $1,2,3,x=5$

This is a variation on the formation of numbers theme. Given $1, 2, 3, x$ in order, and the operations plus, minus, times, divide, and brackets, what single digits can x NOT be? i.e. find a ...
-2
votes
1answer
166 views

Use only 1 2 6 7 to write expressions that equal 31 32 33 34

Construct expressions that equal $31$, $32$, $33$, and $34$ using the numbers $1$, $2$, $6$, and $7$. In each expression, each number must be used exactly once. You addition ($+$), subtraction ($-$), ...
3
votes
2answers
526 views

1 0 1 0 1 0 1 0 1 0 1

Start with the digits:       $1\ 0\ 1\ 0\ 1\ 0\ 1\ 0\ 1\ 0\ 1$ You may then add (only!) these simple arithmetic operators:       $+\ -\ \times\ \div$ You may also ...
29
votes
10answers
9k views

Using only 1s, make 29 with the minimum number of digits

Use the minimum number of ones to make 29. Here is the list of operations permitted: "Standard" operations, such as: $x+y$, $x-y$, $x\times y$, $x\div y$ Negation: $-x$ Exponentiation of two numbers:...
11
votes
2answers
3k views

How should I approach using two 8s and two 3s to make the number 24?

Use two $8$s, two $3$s, and basic arithmetic operators ($ +, -, \times , \div$, parentheses) to make the number $24$. (You may not join numbers together to form new numbers, like $ 8, 3\...
4
votes
1answer
149 views

An unambiguous number puzzle

One is four, two is six Three is one, four is one Five is nine, six is five Seven is nine, eight is nine Nine is two, ten is five Eleven is seven, twelve is eight. What is thirteen? Note: the ...
1
vote
5answers
272 views

Create all numbers from 1-100 by using 1,3,3,7

Create all the numbers from $1$ to $100$ using the numbers $1,$$3,$$3,$ and $7.$ You can only use each number once, except for the $3,$ of which you have two. You can use addition $(x+y),$ ...
12
votes
8answers
3k views

Create all numbers from 1-100 using 1,3,3,6

Create all the numbers from $1$ to $100$ using the numbers $1$,$3$,$3$, and $6$. You can only use each number once, except for the $3$, of which you have two. You can use addition ($x+y$), ...
5
votes
6answers
297 views

2019 to every day of the month

The grumpy professor looked at his class and said - ok so now it is 2019 can you use the four digits individually with *, +, -, /, ^ (raise to the power of) and ! to make each day of the month? You ...
11
votes
4answers
5k views

Create the numbers 1 - 30 using the digits 2, 0, 1, 9 in this particular order!

Inspired by the last year's "2018 four 4s challenge", I thought it's time to welcome 2019 by a similar challenge. This time you have to use the digits 2, 0, 1, 9 in this particular order to create the ...
3
votes
1answer
131 views

Triskadecimal Emojis

[This puzzle is heavily based on one from video game Zero Time Dilemma.] I have one of those weird individualist friends--to give you an idea, he spells his name H-E-N-🔟-R-Y. ...The 🔟 is silent, y'...
12
votes
4answers
4k views

Doubling/tripling puzzle: make 1 from 1536 in as few steps as possible

You start with the number 1536. Your mission is to get to 1 in as few steps as possible. At each step, you may either multiply or divide the number you have, by either 2 or 3; but, only if the result ...
9
votes
2answers
1k views

Ten-digit number that satisfy divisibilty rules for 2,3,4,5,6,7,8,9,10&11

Question: Arrange the digits 1,2,3,4,5,6,7,8,9,0 to make a ten-digit Number that satisfies all of the divisibility rules for 2,3,4,5,6,8,9,10,&11. BONUS: make the number also divisible by 7
19
votes
5answers
753 views

A riddle that has been killing me the whole day

So I'm walking around in London and found the following number riddle. The rules say, that what ever pattern you find, must be true for the rows as well as the columns. The answer in level 1 is for ...