# Questions tagged [mathematics]

A puzzle related to mathematical facts and objects, whose solution needs mathematical arguments. General mathematics questions are off-topic but can be asked on Mathematics Stack Exchange.

3,305 questions
Filter by
Sorted by
Tagged with
68 views

### Show that : $n =E(n*LOG((10*n)/(1+n))+1)$, $n> 0$, n integer? [closed]

Show that $$n =E(n*LOG((10*n)/(1+n))+1)$$ for $n> 0$ , $n$ is integer and E integer part(The ENT function on excel).
100 views

234 views

### Slim at any size?

Recall from ŧhis question that we call a positive integer slimdownable or slim for short if it is part of a sequence of integers where each is followed by itself divided by its length, i.e. its number ...
290 views

### 876925431=2016 Use the four basic operators

Use the four basic operators ×, ÷, +, − and if you want brackets to make: 8 _ 7 _ 6 _ 9 _ 2 _ 5 _ 4 _ 3 _ 1 = 2016. You can use each operator as many times as needed. Concatenation is not allowed.
2k views

### Slimming down integers to a single digit

Slimming down an integer is dividing it, when possible, by the number of its digits. Thus, 315 slimmed down becomes 105, whereas 316 cannot be slimmed down. There are a few numbers that can be ...
280 views

### General orchard planting problem for circles

My previous puzzle asked for the maximum number of 4-point circles attainable from a configuration of $n=10$ points drawn on a plane. I am now interested in generalizations of this puzzle to arbitrary ...
113 views

### Mathematical sequence puzzle

Bob is trying to crack a puzzle. He finds this numerical sequence: 9056, 528, 64 What should he input after 64?
251 views

### Largest range of consecutive integers that can be formed

Using a 10-element multiset of $\{1, 2, 5, 10, 20, 50, 100\}$, what's the largest range of consecutive integer values that can be produced (note that $0$ isn't counted)? For example, I could take ten ...
64 views

### Finding missing number from a table [closed]

This is a brainteaser I recently encountered: Find the missing number in the table: \begin{array}{|c|c|c|c|} \hline 26& 6 & 5 & 4 \\ \hline 13 & 3& 2& 5\\ \hline 25 & 7 &...
176 views

### The meaning of the related numbers

Question: What follows in the sequence below? 10233432943 As a hint, I must say I do not like the single 1 in it. It is unclear if the sequence even started with 1, but the 1 it needed. I had to ...
774 views

### Flipping coins in a circle

We have a set of N coins that are all placed in a circle. They all have "Tails" as their face up side. The coins are all distinct and have numbers (1,2,3...N) written on them. In each move, ...
125 views

### Squares related to circles [closed]

Fibonacci numbers, circles, squares; everything is connected in the digital world. Can you make two squares from a circle? Seven decimals should be accurate enough. Which two numbers am I seeking? I ...
131 views

### Orchard planting problem for squares

The classic Orchard planting problem asks for the maximum number of 3-point straight lines attainable from a configuration of $n$ points drawn on a plane. Here we are interested in a variant of this ...
423 views

### Orchard planting problem for circles

The classic Orchard planting problem asks for the maximum number of 3-point straight lines attainable from a configuration of $n$ points drawn on a plane. Here we are interested in a variant of this ...
101 views

### Formula for the sequence 1, 1, 1, 21, 3, 1, 4, 1, 5, 1, 6,

The sequence 1, 1, 1, 21, 3, 1, 4, 1, 5, 1, 6, ... appeared in one of my tutorial sheets in 2019. I assumed that the fourth term, 21, was a mistake (was supposed to be ..., 2, 1, ...) then it made ...
159 views

### Highest n where an equal number in all cells is (im)possible

Inspired by Board with all 2020s : Zeroes are written in all cells of a n×n board. We can take an arbitrary cell and increase by 1 the number in this cell and all cells having a common side with it. ...
95 views

### Making *9* congruent triangles from the pieces of a triangle dissection

Working on the making 7 congruent triangles from the pieces of a triangle dissection question I realized it's possible to do even better! So here it is for extra points: Use six lines to cut a ...
128 views

### Accomplice numbers

The reverse of a number is the number obtained by reading the initial number from right to left: for example, the reverse of 125 is 521. Two integers are said to be accomplices when these numbers are ...
154 views

### How many steps for matchstick-Lychrel numbers?

The Lychrel number is famous in the recreational mathematics. The process about the Lychrel numbers reverses arrangement of the previous number. Mimicking Lychrel numbers, I would like to devise ...
926 views

### Two player Monty Hall variation

Alice and Bob are going on a game show as partners. In this game, there are three doors, which contain a car, the car keys, and a goat, which are arranged randomly and secretly behind the doors. Alice ...
325 views

### Does “naked set” method always solve a sudoku?

Is always possible to solve a sudoku (that has a unique solution) using only naked pair/triple/quad methods? If not, what about using naked set and hidden set methods combined togheter? I need to know ...
206 views

### Each fruit is a combination of two elements

Hello Puzzling community! Here's a simple pattern question I created recently: 1) Apple = 50 X 2) Banana = 33 G 3) Cherry = 77 Y 4) Dragon Fruit = 137 G 5) Elderberry = ...
167 views

### Lazy Box Sorting

In front of Louis there are 10 boxes containing different foods: tomatoes, (red) herrings, and bananas. The boxes are arranged side by side in a line. Right next to the last box are three bigger ...
1k views

### Board with all 2020s

Zeroes are written in all cells of a $5 \times 5$ board. We can take an arbitrary cell and increase by 1 the number in this cell and all cells having a common side with it. Is it possible to obtain ...
389 views

### Thick as two short planks

That didn't go to plan. You just wanted to help your friend the artist redecorate. In the process you mananged to make an ugly notch in their favorite table, scratch their wall when moving said table ...
James, your friend, has invited you to bet with him. He has a fair die, with $3$ faces showing $0$ and $3$ faces showing $1$. You pay him $\\\$70$. He throws the die$15\$ times, and records the sum of ...