Ordered Pairs

When applying for admission into a university, you will be asked to fill out an information sheet like the one in figure below.

If a student writes Martin, Jose in the name space, the admissions office will interpret this to mean that his surname is Martin and that his given name is Jose. On the other hand, if he writes Jose, Martin, it means his surname is Jose and his given name is Martin. Notice that the order in which the two names appear is important. This is an example of an ordered pair.

A pair of numbers is ordered if the order in which the numbers appear is important.