The population of rodents in a house doubles every day.
Every day 25 rodents are killed.
How many rodents are there if after every 4 days, the number of rodents becomes same again?
An odd day is one which has both its day and month odd for instance 13:5:2000. How many odd days are there in the year?
If there are 4 empty seats in a theatre, how many combinations are there for the number of ways 4 people could sit in these seats?