The first line of the rear box reads “if (123 < 10)”. The first line of the middle box reads “if (12 < 10)”. The full block of code in the front box reads as follows:

if (1 < 10)
{
   cout << 1 << end1;
}
else //n is two or more digits long:
{
   writeVertical(1 / 10);
   cout << (1 % 10) << end1;
}

The first four lines are annotated “No recursive call this time”.