Value of the expression in which we replaced each of the variables with numbers from their defined domains.
Talking about the value of a digit is a short form to refer to the numerical value associated with a digit in the case of a number that only has one digit.
Example
Consider the algebraic expression 2x + 4xy\(^{2}\) in which the variables x and y take values from the set of integers.
The numerical value of this expression, when x = 5 and y = 10, is 2010, because: 2 × 5 + 4 × 5 × 102 = 2010.
Educational Note
When a number has more than one digit, the expression “the sum of the digits of a number” should be replaced by “the sum of the numerical values associated with each digit in a number“.