I am thinking of a 5 digit number that when tripled is a perfect square.

Also, when the 5 digit number is split, the first number is double the second one. What is the five digit number?

(Splitting the 5 digit number into two numbers means 12345 into 1 and 2345 or 123 and 45.)

The answer is 13467 (134 is double 67).

Easily verified with the following C code:
(which shows in the second column the only integral square root...)

13467*3 = 40401 which is the square of 201.

#include "stdafx.h"
#include "math.h"

int main(int argc, char* argv[])
{
int x, y;
for (x=50; x<100; x+=1)
{
y=(200*x)+x;
printf("%d\t%f\n",y,sqrt(3*y));
}
return 0;
}

Posted by Not Applicable on 2003-08-20 14:41:51