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What US State is triply landlocked --( a resident must cross three states to reach an ocean, gulf, or bay)?
(No Solution Yet, 2 Comments) Submitted on 2018-02-19 by Ady TZIDON    

Definition: Strictly non-palindromic number or SNP number n is a number not palindromic in any base b with 2 ≤ b ≤ n-2.

Equipped only with the above definition you are asked to perform the following tasks:
1. Show that 47 is a SNP number.
2. Write down the 1st 7 members of an increasing sequence of SNP numbers.
3. Explain the reason for defining b=n-2 as the upper limit.
4. Prove that all SNP numbers above 6 are prime, but not all primes are SNP numbers.
(No Solution Yet, 3 Comments) Submitted on 2018-02-18 by Ady TZIDON    

Difficulty: 3 of 5 Let's make a deal (in Numbers) Rating: 5.00
DEAL * DEAL = ----DEAL
Replace dashes by decimal digits,
using reasoning only.

There is only one solution!
(Solution Posted, 1 Comments) Submitted on 2018-02-17 by Ady TZIDON    

<this word> has one I, two Ls, three Ns, four Es, and five Ss.
Find it and its meaning.

Source: Discovered by Sir Jeremy Morse.

(Solution Posted, 7 Comments) Submitted on 2018-02-16 by Ady TZIDON    

Two concentric circles of radius R and r, with R>r are both intersected by the same secant line. The points of intersection, in order, are A,B,C,D.

Prove AC*CD is constant.

(No Solution Yet, 2 Comments) Submitted on 2018-02-15 by Jer    

Arrange 4 fours into various expressions to generate all integer numbers, from 1 to 112 inclusive like:

1 = 44 ÷ 44
2=sqrt 4 - (4 - 4) x 4
3 = (4 + 4 + 4) ÷ 4
4 = 4 + 4 × (4 - 4)
... ...
7= 44/4-4
... ...
19=4!-4-4/4
... ...
100=4*4!+sqrt(4*4)
etc

Allow use of concatenation, +, -, x, /, sqrt, exponentation, factorial,decimal fractions, overline & brackets.


Source: Inspired by Martin Gardner statement.

(No Solution Yet, 6 Comments) Submitted on 2018-02-14 by Ady TZIDON    

From a set of 2n+1 consecutive integers a certain number, say x, is selected in a way that the remaining n pairs can be arranged as couples having the same sum.

What are all the possible values of x making such task doable?
(Solution Posted, 6 Comments) Submitted on 2018-02-13 by Ady TZIDON    

At a meeting of the Young Historical Society (YHS) in a local library the number of children present was three times the number of parents.
At this meeting, each boy borrowed 12 books from the library, each girl borrowed 17 books and each parent borrowed 9 books.
In total 305 books were borrowed.

How many girls were there at the YHS meeting?

(Solution Posted, 5 Comments) Submitted on 2018-02-12 by Ady TZIDON    

In the equation A*B=C :
A is an 8-digit number without repeated digits
B is a single digit, not present in A
C is a number containing all non-zero digits.

Sample solution: (A, B, C)= 51249876*3=153749628

Find additional solutions.

(Solution Posted, 3 Comments) Submitted on 2018-02-11 by Ady TZIDON    

The digits of this six digit number N are A,B,C,D,E,F in some order.

Given that :
DEF/ABC is an integer number
and
N=ABC*DEF

find all possible values of N.

(Solution Posted, 1 Comments) Submitted on 2018-02-10 by Ady TZIDON    

six*cinq= trente

The above 9-digit alphametic is solvable (go for it), but the 10-letter English equivalent (six*five= thirty) is not!

Why not? Where's the contradiction?

(Solution Posted, 3 Comments) Submitted on 2018-02-09 by Ady TZIDON    


Consider a semi-circle of radius r.
A curve C is drawn such that at any point P on C, the distance between P and the semi circle's base equals the length of a line segment from P perpendicular to the given semi-circumference.

Derive C's equation.

(No Solution Yet, 2 Comments) Submitted on 2018-02-08 by Kenny M    

Difficulty: 3 of 5 Square pairs (in Just Math) Rating: 5.00
Let's denote by p(n) the greatest square less than or equal to n,
n being a positive integer.

List all pairs (m,n), for which:(2m+1)*p(2n+1) = 400; m being less than n.

(Solution Posted, 3 Comments) Submitted on 2018-02-07 by Ady TZIDON    

A four-digit PIN number aabb, where a and b are distinct digits, is a multiple of 15.

Which values of a are not possible?

(Solution Posted, 3 Comments) Submitted on 2018-02-06 by Ady TZIDON    

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