Any number which
corresponds to a length on a number line is a real number, such
as 3, 8.4, -9.2, 0, 26.98732, √2. Real numbers can be written using
decimal notation, whether the decimal terminates, is recurring,
or goes on for ever without the pattern of digits repeating, such
as

3.745 28.131313131313... 812.01001000100001...

A real number, also called just a real, is a number which can be
written out as a decimal, even though it might take forever to do
so. Whole numbers, fractions, irrational and transcendental numbers
are all real.