February 13, 2003
@ 11:58 PM
After two tries it was obvious that
all possible answers to the question "What do you get
if you choose any two digit number, add both digits
then subtract from the original?" were given the same
symbol so it didn't matter which two digit number you
picked. The answer would always be one of the series
The real problem, of course, is deriving the formula
for this if one exists (given that it would be
trivial to brute force this). Anyone game for
that?
The code below reveals an interesting characteristic
about the numbers. Think lives of a cat.
using System;
using System.Collections;
public class Sample
{
public static void Main(){
ArrayList list = new
ArrayList();
for(int i = 10; i
<100; i++){ <br> int j =
doMagic(i);
if(!list.Contains(j)){
list.Add(j);
}
}
list.Sort();
//print all possible
numbers that satisfy criteria
foreach(int i in
list){
Console.WriteLine(i);
}
}
static int firstDigit(int
num){ return num/10;}
static int secondDigit(int
num){ return num%10;}
static int doMagic(int
number){
return number -
(firstDigit(number) + secondDigit(number));
}
}