The expression "Eight times the sum of a number and three" can be translated into a mathematical expression as follows:

Let the unknown number be represented by $x$.

The sum of the number and three is $x + 3$.

Eight times this sum is $8(x + 3)$.

So, the expression is $8(x + 3)$.

Would you like details or have any questions?

Here are some related questions you might find interesting:

1. How do you solve the equation $8(x + 3) = 24$?
2. What happens if you expand $8(x + 3)$?
3. How do you simplify $8(x + 3) - 5$?
4. Can you write an expression for "Six times the difference between a number and five"?
5. How do you solve $8(x + 3) = 0$?

Tip: When translating words into algebraic expressions, always identify the operations (like "sum" or "times") and the numbers involved.