# 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)...
702 views

### 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 ...
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 ...
244 views

### 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
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 ...
135 views

### 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 ...
2k views

### 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, $+ - * /$ ...
188 views

1 vote
1k views

### 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 ...
1k views

### 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 ...
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 ...
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 ...
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 ...
2k views

### 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 ...
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 ...
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 ($+, -, \times, \div$...
106 views

### 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. ...
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 ...
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!? ...
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 ...