Let A be the set of primes less than 6, and B be the set of positive odd numbers less then 6. How many different sums of the form a a + b are possible, if a is in a and b is in B?
A man walks 2 km towards north. Then he turn to east and walks 10 km. After this he turn to north and walks 3 km. Again he turn towards east and walks 2 km. how far is he from the starting point?
Five bells begin to toll together and toll at intervals of 36, 45, 72, 81 and 108 seconds. After what interval of time will they keep on tolling together ?