# Questions tagged [formation-of-numbers]

For puzzles about forming numbers using other numbers and mathematical operations. Use with [mathematics]

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### The operator acts on two numbers to give the following outcomes [closed]

The operator • acts on two numbers to give the following outcomes: 20•2=51 9•8=0 7•3=66 23•14=0 25•2=56 30•12=364 16•9=259 15•22=0 What is the value of 20•1? A. 0 B. 19 ...
401 views

### Create all of the integers from 1 to 100 using 1, 5, 5, and 7

All four numbers must be used for each solution, but they may appear in any order. Permitted: the 4 basic mathematical operations, square root symbol (maximum twice per solution, and the 2 is implied)...
• 41
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### Compact mathematical expression [closed]

Make a mathematical expression whose value is equal to 2 that uses all the digits 0, 1, 2, ... 9 exactly once and uses as few other mathematical symbols as possible.
218 views

### Four 4s to make a 4 [closed]

Shown below is an equation with four 4s on the LHS and a 4 on the RHS with 4 rectangular boxes and 3 ovals. Make this equation correct by replacing the rectangular boxes by 4 separate single items ...
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178 views

### Solve for 69 using only 1 9 9 2 in that order [closed]

You must use all the digits of $1 9 9 2$ in that order to come up with $69$ as the answer. For example $- (1 + \sqrt {9})! + 92 = 68$ but you must solve for $69$.
188 views

### Using Prime numbers to get 100 and 1000

Using the digits 1 to 9 exactly once create a set of one or two digit prime numbers. Use those prime numbers and the math operations + - / * and parantheses to get 100. Then use those exact same ...
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### How do you produce the number 5, using only 3 eights?

How do you produce the number 5, using only 3 eights? The 4 operations (+ - x and division) + square root and factorial are allowed but no extra numbers (no squaring).
426 views

### How do you get the number

How do you use the format 1_*_ _ _ _ _ _ _ _ to get 222,222,222 using only the numbers 1-9 only once
• 109
803 views

### Paris and Wife Matchstick

Here are two matches dates that I hold with love in my heart: The current sum is 1970 + 1997 = 3967. You must requisition at most 10 matches so that the sum is "as big as possible". We will ...
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### Alien decimal numeral system, part II

(continuation...) My alien friend said "do you think our system is strange? You need to have a look at our neighbour country, this is how they do it...", and then he showed me their ...
1k views

### Alien decimal numeral system

During our travels around the galaxy we found many alien cultures with different number systems. However, this specific civilization was quite interesting: they had a decimal numeral system, just like ...
183 views

### Some blissfully ignorant math?

I was playing around with the code for my game the other day in an effort to create some unique effects. One thing I created was what I called an "ignorant assignment" in which I applied ...
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### Obtain numbers from 0 to 9 with the digits of 2022 in that order

The title says (nearly) all. Write the digits $2$ $0$ $2$ $2$ in that order and apply mathematical operators to obtain all values from 0 to 9. What's allowed: The four basic operators, $+ - * /$ ...
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1 vote
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### Make 1-100 using 2 0 2 2

You may use the following: Addition [e.g. 2+2] Subtraction [e.g. 2-2] Multiplication [e.g. 2x2] Division [e.g. 2/2] Decimal point [e.g. 2+.2] Exponents [e.g. 22] {tetration is NOT allowed} Square ...
403 views

### Largest pair of consecutive numbers, not greater than a million, that can be expressed with four fours [closed]

What is the largest pair of consecutive numbers, not greater than a million, each of which can be expressed using precisely four fours and an assortment of standard operators (including concatenation, ...
299 views

### Make 93 using 2, 0, 2, 2 and a least powerful set of operations [closed]

Use some mathematical operations to make an expression equal 93. You must use each one of the digits 2, 0, 2, 2 exactly once, and no other digits. To score the solutions, your set of operations used ...
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### Find three ways of forming the number 100 using 3,3,5,7

As it says in the title. Rules: anything not explicitly allowed is forbidden. use 3, 3, 5, 7 and multiplication, division, sum, difference, unary minus, and exponentiation in any order. Parentheses ...
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692 views

### Calculation - the hard way

This is a puzzle I love to play with my math students and I hope you will enjoy it too: You are given the numbers 1, 2, 3, 4, and 5 exactly once. Your target is a number, e.g. 36. Can you create a ...
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124 views

### How to open the lock from this safe?

The puzzle is as follows: The figure from below shows a lock mechanism used to store sensitive data microfilms from a certain lab. This mechanism is magnetic and consists in numbered buttons which ...
• 1,495
97 views

### A challenge to make 1 - 100 [closed]

So this challenge is you have (don't have to) make the numbers 1 - 100 by using the numbers 1, 3, 4, 6 only once. I'm stuck on how to make 54. Can anyone help me? P. S. You can use +, -, ÷, x, ! And ...
446 views

### Not so boring numbers

This is inspired by this and this and more similar ones. Let us consider formation of a given positive integer N by the following rules You may use only one digit, which one is your choice and you ...
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### Make 38 using the least possible digits 8

This is a follow up question to this one, which was: Make the number 1998 using the minimum amount of digits 8. Your allowed operations are +, -, *, /, ^, % (percent). You need not use only integers ...
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1 vote
2k views

### Make numbers 1 - 40 using digits 2, 0, 2, 1

Using only the digits in the year 2021 and basic mathematical operations (+, -, × and ÷), how many of the numbers from 1 to 40 can you make? Not all of the numbers are possible! You may use each digit ...
174 views

Make the 41 integers between -20 and 20 (-20, -19, ..., 0, 1, ...20) using only the four basic arithmetical operations, square root, the floor function, and, Surprise Surprise, exactly 3 π’s. No more ...
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833 views

### Make numbers from 1-10 with 5 3s

In this puzzle book, I came across a question that goes like this: Make the numbers from 1-10 using 5 3s. Rules: You are only allowed to use the four basic arithmetic operators ($+, -, \times, \div$...
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### Form a magic square with assorted numbers

Arrange the following numbers in a way such that all rows, columns and the diagonals add up to the same number. ...
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133 views

### Use only πs to get e

I am taking this puzzle from inspiration from the Four Fours to get Pi puzzle. The puzzle rules are just slightly different. Here are the rules: You are trying to get as close to e as possible with ...
• 1,016
140 views

### Numbers side by side

Ok, so here's a little puzzle I got. I have five different numbers. They all have different amount of digits. If you place them side by side you see the number 32767 How is this even possible!? ...
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826 views

### Sum of digits of sum of digits of sum of digits

The following question was asked in a competitive exam for which I am preparing and I was unable to solve it (in fact I am completely clueless about it). So, I am asking for help here. Given a number ...
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