The best way to learn R is to download the program and start using it. The interactive use of R involves typing and submitting expressions at the command prompt. By commands I mean a valid expression that can be evaluated by R without errors.
R has the most commonly used math operators.
A vector is collection of elements of the same mode . However, if one vector is short in error, no error message will appear because the elements of the shorter vector are recycled to make the vectors of the same length. Sometimes, you intend to use a numeric vector in several calculations but you do not want to re-type the entire vector each time. The solution is to assign a name to this vector. More commonly, however, is to use the vector name in operations involving other data objects.