# What Is A Coefficient In Math?

The coefficient definition is a numerical factor for a literal expression or a constant factor for a variable value.

For example, in a problem:

*a**1**x**1* + *a**2**x**2* + *a**3**x**3* + …

*a**1* is a coefficient at variable *x**1*.

If the expression consists of one number and several letters multiplied by each other, then this number will be the coefficient of the whole expression. The number of letters does not matter – the number can be multiplied by one letter, two or five at once, it still remains a coefficient.

Let’s consider the following expressions:

- 5*a. There is one number “5” and one letter “a”, and they are multiplied by each other. Accordingly, the number “5” will be the coefficient of the whole expression.
- 7*b*c. Here we see an expression of one number and two letters at once. But since the multiplication between them is preserved, the number “7” also remains a coefficient.
- 6*9*a*b. To find the coefficient here, multiply 6 by 9, and 54 will be the coefficient of expression.