The task is to continue the pattern by subtracting 10 each time.

Given numbers are:

429 → 419 → 409 → ___

Subtracting 10 from 409:

$409 - 10 = 399$

The next number is 399.

Let me know if you want further clarification or have additional questions!

Here are 5 related questions to explore this further:

1. What happens if we subtract another 10 from 399?
2. How would this sequence look if we start with a different number, such as 500?
3. What if we subtract a different value, such as 15, instead of 10?
4. How can this sequence be represented as an arithmetic sequence formula?
5. Can you find the sum of the first four terms of this sequence?

Tip: Arithmetic sequences follow a simple formula to predict any term in the sequence!