#include <cmath>
#include <iomanip>
#include <iostream>

using namespace std;

int main ()
{
double number [100000];
int i=0;

while ( ! cin.eof())
{
cin >> number [i];
i++;
}

for( int j=i-1; j>=0; j--)
{
cout<< setprecision (4) << sqrt(number[j])<<endl;
}

return 0;
}

here's my program but I don't know what's wrong.. when i put the number of elements of the array to 140000 it says "stack overflow", when i put 10000 it says wrong answer.

All local variables are allocated in stack. Array "number"[] is local, because it is described in function "main". Standard size of stack is 1 MB, size of double variable is 8 bytes. So it isn't enough space to allocate all array with 140000 elements. You should increase stack size.
http://acm.timus.ru/help.aspx?topic=cpp

#pragma comment(linker, "/STACK:16777216")

Edited by author 22.05.2014 15:07