There is no four digit number where the ones is twice the tens,
the hundreds is five less than the ones, and the thousands is the
sum of the tens and hundreds.
int ones, tens, hundreds, thousands;
for (thousands=1; thousands<10; thousands++) {
/**/ for (hundreds=0; hundreds<10; hundreds++) {
/**/ /**/ for (tens=0; tens<10; tens++) {
/**/ /**/ /**/ for (ones=0; ones<10; ones++) {
/**/ /**/ /**/ /**/ if (ones != 2 * tens) break;
/**/ /**/ /**/ /**/ if (hundreds != ones - 5) break;
/**/ /**/ /**/ /**/ if (thousands != tens + hundreds) break;
/**/ /**/ /**/ /**/ printf ("dd\n", thousands, hundreds, tens,
ones);
/**/ /**/ /**/ }
/**/ /**/ }
/**/ }
}