Final answer:
The mathematical expression for 'three times the absolute value of the sum of a number and six' is 3 |n + 6|, where n represents the number.
Step-by-step explanation:
The expression to represent the given statement is: 3 |n + 6|.
To construct this expression, we start with the 'sum of a number and six', which is represented mathematically as n + 6. The absolute value of that sum is written as |n + 6|. Finally, the entire phrase 'three times the absolute value of the sum of a number and six' means that we multiply that absolute value by three, resulting in 3 |n + 6|.