Solution to Sudoku no 722

Sudoku no 722 (Easy)

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Solution to Maths Problem no 2

Here is one way to work it out, which will only make sense if you can program in C:

andrew@ASUS-Laptop:~/Maths_Problems$ cat multiply.c
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

void para_a (void);
void para_b (void);
void para_c (void);
void para_d (void);

/* Global variables. */

int a;
int b;
int c;
int d;

int main ()
{
para_a();
}
void para_a ()
{
for (a = 1; a <= 9; a++) para_b();
}
void para_b ()
{
for (b = 0; b <= 9; b++) para_c();
}
void para_c ()
{
for (c = 0; c <= 9; c++) para_d();
}
void para_d ()
{
for (d = 0; d <= 9; d++)
  {
  if ((a!=b)  && (a!=c) && (a!=d) && (b!=c) && (b!=d) && (c!=d))
    {
    if (9*(1000*a+100*b+10*c+d) == 1000*d+100*c+10*b+a)
      printf("%d %d %d %d\n", a, b, c, d);
    }
  }
}
andrew@ASUS-Laptop:~/Maths_Problems$ cc -o multiply multiply.c
andrew@ASUS-Laptop:~/Maths_Problems$ ./multiply
1 0 8 9
andrew@ASUS-Laptop:~/Maths_Problems$

Maths Problem no 2

Find a four digit number which you can multiply by 9 to give the same four digits in reverse order. All four digits must be different and the first digit of the original number must not be zero:

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Solution to Sudoku no 721

Sudoku no 721 (Tough)

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Solution to Maths Problem no 1

Maths Problem no 1

Puzzles like this appeared in Computer Weekly in the '80s and '90s. As they were in a computing magazine I often wrote a BASIC program to solve them. However, my son worked this one out using pencil and paper in around 15 minutes. I created it using Oracle Database Version 18 Express Edition.

Replace the letters in the addition sum below so that the answer is correct. Use each of the numbers 1 to 9 exactly once and assume that O=1, R=5 and E=2:

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Chess Solution no 22

 

1. Rc8+  Kg7

2. Bf6+  Kh7

3. Rh8+  Kg6

4. Rg8+ 1-0 (as black will lose her bishop)

Chess Puzzle no 22

The position below is from Anna Muzychuk versus Zhongyi Tan, FIDE Women's World Cup, 2023, Baku, Azerbaijan. It is white's turn to play. Try to work out how the game continued:

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Solution to Sudoku no 720

Sudoku no 720 (Extreme)

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