Practice Type Conversion

Write a function calculate_score(num_str, multiplier) that receives a numeric string num_str (e.g., "10") and a numeric multiplier (float or int). The function should:

1. Convert num_str to an integer.
2. Multiply it by multiplier.
3. Truncate the product to an integer (drop any decimal part).
4. Return a message string exactly formatted as "Final score: X" where X is the truncated integer.

Examples

calculate_score("10", 2.5)  # returns "Final score: 25"
calculate_score("3", 1.9)   # returns "Final score: 5"