The proper noun is the word Spain, the name of the country. A
person of Spain is a Spaniard, also a proper noun. People or things
of or from Spain are described by the proper adjective Spanish.
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Prime numbers don't have proper factors.
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The proper factors of 99 are: 1, 3, 9, 11, 33. A proper factor
is any factor of the number that is not itself.