More than twenty years ago, Tim asked his grandfather who was celebrating his birthday that day: "How old are you now?" Grandfather smiled and said: "Add the digits of my year of birth and multiply the answer by 4." Tim would have looked so uncomfortable that his Grandfather immediately added, "By the way, this trick also works with the year we have on the calendar now." What was grandfathers age?

It can't be seen

it's owners don't use it

and everything has one

Suppose you have two bottles with equal perimeter, thickness and height. One bottle is cilindrically shaped, the other one has the shape of a rectangular box with a square shaped bottom. In which of the bottles fits more milk?