Let’s go through the calculation step by step:

1. Start with 1000.

2. Add 40 → 1000 + 40 = 1040.

3. Add 1000 → 1040 + 1000 = 2040.

4. Add 30 → 2040 + 30 = 2070.

5. Add 1000 → 2070 + 1000 = 3070.

6. Add 20 → 3070 + 20 = 3090.

7. Add 1000 → 3090 + 1000 = 4090.

8. Add 10 → 4090 + 10 = 4100.

Final Answer: 4100

This puzzle is a common mental math trick. Many people mistakenly arrive at 5000 because their brain adds incorrectly when dealing with numbers in the 1000s and smaller values like 40, 30, 20, and 10. However, when carefully calculated, the correct answer is 4100.