The mathematical approach of adding a literal number to one or more literals is called the addition of literal numbers. It is also called as the summation of literals.
Literal numbers are often involved in addition in algebra and there is a mathematical procedure to add one literal to another literal number to obtain sum of them. It is a basic mathematical operation in algebra with literals and most useful for learners in studying the algebra.
There are two special cases in adding literal numbers in algebra.
In this special case, two or more same literals involve in addition and they can be directly added like numbers but there is a rule for it. First count the total number of same literals in addition. Write the total of them first and then write the literal once in this type of cases.
$(1) \,\,\,\,\,$ $a+a$
Two $a$ literals are involved in addition. They are usually called two $a$ literals and it is written as $2a$.
$\implies a+a = 2a$
$(2) \,\,\,\,\,$ $b+b+b$
Three $b$ literal numbers are involved in addition in this example. So, the sum of them is three $b$ literals and it is written as $3b$ in mathematics.
$\implies b+b+b = 3b$
$(3) \,\,\,\,\,$ $c+c+c+c$
In this example, four $c$ literals are involved in addition and the sum of them is four $c$ literals and it is expressed as $4c$ algebraically.
$\implies c+c+c+c = 4c$
Two or more various literal numbers are often involved in addition. The letters cannot be added directly like numbers because they are different literals. The sum of such different literals is written as an algebraic expression.
$(1) \,\,\,\,\,$ $a+b$
$(2) \,\,\,\,\,$ $a+b+c$
$(3) \,\,\,\,\,$ $a+b+c+d$