Show that given any \(6\) numbers, at least two of them will have the same remainder when divided by \(5\).
Show that given any \(3\) numbers, there will be two of them so that their difference is an even number.
Show that given \(11\) numbers, there will be at least \(2\) numbers whose difference ends in a zero.
Three whole numbers are marked on a number line. Show that for two of these marked numbers, the point halfway between them is also a whole number.