We’re rewarding the question askers & reputations are being recalculated! Read more.

Questions tagged [arithmetic]

For puzzles involving addition, subtraction, multiplication, or division.

Filter by
Sorted by
Tagged with
1
vote
2answers
134 views

Free Assignment: Longest Word Worth a Million

This is very much inspired by this question. Take the first 26 primes and relate each one to a letter of the alphabet. On this occasion, you may choose how each number is mapped to each letter (...
1
vote
1answer
140 views

Please help me to identify the pattern

$(A)72$ $(B)18$ $(C)9$ $(D)19$ Source:My coaching DPP The question asks you identify the pattern and find the missing character. I have been trying to solve this problem from a long time but I ...
8
votes
5answers
3k views

Longest word worth at most a million

An old and popular puzzle, recently revived on Twitter by Alex Bellos, Chris Smith, and others, asks to take the first 26 primes, relate each to letters of the alphabet (A = 2, B = 3, C = 5, ..., Y = ...
-4
votes
0answers
132 views

How do I solve this problem?

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
1answer
100 views

How do I solve this multiplication problem?

I am trying to answer this puzzle my friend created and sent to me - which of the five potential answers is correct, and why? $ 10 \times 5 = 60 \\ 6 \times 12 = 72 \\ 8 \times 3 = 44 \\ 5 \...
-2
votes
1answer
123 views

Missing Number Picture Puzzle

This is is logical reasoning puzzle in which your challenge is to find the relationship among the given numbers and then find the value of the missing number. Source: https://www.funwithpuzzles.com/...
6
votes
3answers
637 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.
4
votes
2answers
222 views

Primes from arithmetic and geometric progressions

The five primes, 131, 157, 211, 349, 739, are neither in arithmetic or geometric progression, but are instead the sum of the corresponding terms of two progressions of five terms each, one arithmetic ...
10
votes
1answer
254 views

What is a Commutative Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it a Commutative Word™. Use ...
11
votes
1answer
451 views

What is a Heptagon Number™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with Number version puzzles. If a number conforms to a special rule, I call it a Heptagon Number™. Use the following ...
4
votes
2answers
153 views

Rearrange these 9 digits - combinatorics puzzle

4 3 2 7 1 9 6 5 8 Can you rearrange these 9 digits so that in all of the 8 directions the difference between one of the digits and the sum of the remaining two shall always be the same? In the ...
29
votes
1answer
1k views

What is a BEN Number™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with Number version puzzles. If a number conforms to a special rule, I call it a BEN Number™. Use the following examples ...
0
votes
2answers
173 views

Find the number that does not fit into the pattern shown below

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 12 34 56 78 910 1112 1314 1516 1718 1920 2122 2324 2526 2728 2930 3132 3334 3536 Each row forms a set which implements a pattern. The two patterns ...
7
votes
2answers
917 views

What is a Finale Number™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with Number version puzzles. If a number conforms to a special rule, I call it a Finale Number™. Use the following examples ...
8
votes
2answers
260 views

What is a Valid Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it a Valid Word™. Use the ...
10
votes
2answers
586 views

A Magic Flying Saucer

Place 19 different positive integers on the vertices of this graph so that the 13 products of three numbers in a straight line are all equal. Do so in such a way that the product is as small as ...
11
votes
4answers
2k views

A Magic Diamond

Place 15 different positive integers on the vertices of this graph so that the ten products of three numbers in a straight line are all equal.
7
votes
2answers
925 views

Big number puzzle

I saw this on rec.puzzles many years ago, but can't find the reference to credit the source. I am thinking of a large number. If you want to multiply it by a two digit number $ab$ with $a \lt b$, ...
5
votes
2answers
602 views

What is a Trio Word™?

This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles. If a word conforms to a special rule, I call it a Trio Word™. Use the ...
2
votes
3answers
127 views

Express the Squares of first 20 Numbers with only numbers found in their Sum of Digits

Allowed Operations ...Addition, Subtraction, Multiplication, Division, Exponentiation, Simple Factorial. Left and Right Brackets allowed. Expression should involve minimum number of total characters: ...
3
votes
2answers
363 views

Is it True that Two + Two = 2? If so, what is Ten + Ten and Nine + Nine?

Given: SIX + ZERO = 4 TWO + THREE = 15 FIVE + SIX = 88 ONE + TWO = 83 TEN + TWO = 13 If so, is TWO + TWO = 2 correct? What is TEN + TEN ? NINE + NINE ? Hint 1
-5
votes
2answers
145 views

Numberless Sudoku with Just a Letter and Symbol Combination

A Standard 9x9 Sudoku uses the digits 1 to 9. You are only allowed to use a single letter(say T) and a symbol of your choice to represent the digits 1 to 9. Rules should be well defined and the ...
5
votes
2answers
174 views

Standard Sudoku Specialized with just 2 Primes

A standard 9x9 Sudoku uses the digits 1 to 9. You are only allowed two distinct primes to represent 1 to 9. Find out the minimum number of characters (digits + signs) needed to construct a Sudoku ...
1
vote
2answers
90 views

Make N N N equal to 6 where N is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 [duplicate]

Using standard mathematical symbols, (i.e. no other letters or numbers), make the following true: ...
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 (-), ...
13
votes
1answer
1k views

Primes in a Diamond

Label the vertices of this graph with numbers 1 to 16 in such a way that the edges between any two vertices whose sum and absolute difference are both primes are precisely the edges of a hamiltonian ...
5
votes
1answer
84 views

Cross-number of two, three and four-digit numbers

In this cross-number two-digit numbers are prime numbers, three-digit numbers are square numbers and four-digit numbers are palindromic numbers.
6
votes
2answers
1k views

Father and Son and Grandsons

The sum of the ages of a father, his son, and his two grandsons is 181. The father´s age has a common divisor greater than 1 with the ages of each of his three descendants, but not two of the latter ...
18
votes
5answers
869 views

Primes less than 100 in a 4 x 4 board

Place one of the digits (0 to 9) in each of the cells of a 4 x 4 board so that as many as possible of the 25 primes less than 100 divide at least one of 10 positive 4-digit numbers that can be read ...
10
votes
1answer
409 views

Zero, One, Two, Three, etc

Find a solution to the following system of simultaneous equations. All letters stand for integers (positive, zero, or negative), and different letters are different integers. The preferred solution ...
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 ...
20
votes
4answers
825 views

Consecutive integers around a circle

Find a block of positive consecutive integers that can be placed around a circle in some order so that any two adjacent numbers always have a common divisor greater than 1.
2
votes
1answer
104 views

Pairwise coprime numbers in a 3 x 3 board

Find all the ways of placing all the digits 1 to 9 in the cells of a 3 x 3 board in such a manner that the seven three-digit numbers that can be read horizontally (from left to right), vertically (top ...
3
votes
1answer
172 views

Making Branko Grünbaum's symmetrical 5-set Venn diagram magic

Place integers 1 to 31 in the 31 regions of Branko Grünbaum's symmetrical 5-set Venn diagram so that the sum inside any of the 5 sets is the same.
6
votes
1answer
574 views

Do the maths to call my name

My first one is my length. My second one is a bit closer to my third one than to my first one. My third one is my first and second together. My last one is four times my first one. ...
74
votes
4answers
6k views

The mother of all age-of-the-captain riddles

A few days ago, as I was delving into the mess in my grand parents' attic, I found an impressive ancient book that was written in a language that I had never seen before. "This book is a collection ...
13
votes
5answers
630 views

Labelling a Snow Flake Graph to Attain Minimum Sum

Label the vertices (or nodes) of this graph with positive integers so that any two nodes are joined by a edge (or line) if and only if the corresponding integers have a common divisor greater than 1 (...
1
vote
5answers
267 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 $(x+y),$ ...
10
votes
5answers
857 views

Divisible Dates

The day of the month, and the month of the year, often simultaneously divide the year. Most recently it happened on January 3, 2019 because both 1 (January) and 3 divide 2019. In our era, since 1/1/...
7
votes
1answer
236 views

A Tetrad Puzzle: Find The Key

I made this to test some ideas for a game I'm developing. Feedback would be appreciated. What is the key?
2
votes
1answer
627 views

Help solving a math puzzle table

I am struggling to find the answer. Here is the source: math logic puzzle phone app.
1
vote
1answer
146 views

From 2019 to digits

Is it possible to obtain the digits from 0 to 9 starting from 2019 and using its digits in the same order, together with the usual operations +, *, -, /, concatenation of digits, and the less usual ...
7
votes
3answers
790 views

Gaby and Jack's Number Guessing Game

Gaby, a good mathematician, thinks of a whole number between 1 and 100 inclusive. What is the least number of questions Jack needs to ask her, and what questions should those be, if he is to work out ...
-3
votes
2answers
699 views

Brain Testing Logical Reasoning Puzzle

Can you answer this logical puzzle? Puzzle Source: https://www.funwithpuzzles.com/2018/12/brain-testing-logical-reasoning-puzzle.html
6
votes
2answers
320 views

A partition of 80 into seven parts

The sum of seven positive integers, not necessarily distinct, is 80. If placed appropriately on the vertices of this graph, two of them will be joined by an edge if and only if they have a common ...
12
votes
3answers
776 views

The Mxied Atdiiodn

It has been swohn that to raed a txet the oedrr in which the lrtetes of each idniaduvl word aepapr is not ipmotanrt, so lnog as the fsrit and lsat ltetres are the correct oens. This is not the case ...
7
votes
2answers
581 views

Primes and Squares

Place a different prime or square number on each of the fifteen disks below so that the number in any disk that lies on two others is the sum of the numbers in those disks. Do so in such a way that ...
2
votes
1answer
73 views

Fly flight estimation [duplicate]

John and Peter are two friends living in two nearby villages 15km apart. One day they arrange to meet, but little do they know, a “flies marathon flyer”, an irritating fly, decides to play a game. ...
8
votes
2answers
676 views

Four Magic Ellipses

These four ellipses represent four sets and all the possible ways they can intersect (a Venn diagram, in other words). There are 8 regions inside each ellipse, and 15 regions altogether. Is it ...
6
votes
2answers
334 views

The Magic Letter H

Place seven different positive integers on the empty disks of the H figure below so that the product of the three numbers in any straight black line is always the same. Now place seven other numbers ...