Let the three consecutive even numbers be represented as $x$, $x + 2$, and $x + 4$. The equation based on their sum is:

$x + (x + 2) + (x + 4) = 258$

Simplifying this, we get:

$3x + 6 = 258$

Subtract 6 from both sides:

$3x = 252$

Now, divide by 3:

$x = 84$

Thus, the three consecutive even numbers are $84$, $86$, and $88$. The least number is:

$\boxed{84}$

If you have any questions or need further details, let me know! Here are some related questions you might consider:

1. What are the next three consecutive even numbers after 88?
2. How would the problem change if the sum was 300 instead of 258?
3. Can you find the sum of three consecutive odd numbers?
4. What is the relationship between consecutive even and odd numbers?
5. How can you represent consecutive integers mathematically?

Tip: To solve problems involving consecutive numbers, always express them in terms of a variable and set up an equation based on their relationships.