Just think about it. There are 7 days. If I spread the birthdays as much as I can then with 35 people each day has 5 people born on it. With one more person one of those days is going to have to have 6 people born on it.
What is pigeon hole principle ? using these principle show that in any group of 36 people, we can always find 6 people who were born on the same day of week.
somebody please help