Does an expression have to contain a variable?

Question

like is a little problem with all numbers a variables.

Answer 1

No.

0 is an expression.

Answer 2

In mathematics, the word expression is a very general term for any well-formed combination of mathematical symbols. For example,

x2 + 3x − 4

is an expression, while

    )x) / 0

is not, because the parentheses are not balanced and division by 0 is undefined.

Common examples of mathematical expressions include arithmetic expressions

2 + 3,

and algebraic expressions such as polynomials

x2 + 3x − 4,

rational expressions

2 / x + x / 2,

and equations

x + 2 = 5

An expression does not have to contain a variable.

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