1. **State the problem:** Calculate the product of 400 and 0.05. 2. **Formula used:** Multiplication of two numbers is given by $$a \times b$$. 3. **Apply the formula:** Here, $$a = 400$$ and $$b = 0.05$$. 4. **Calculate:** $$400 \times 0.05 = 20$$. 5. **Explanation:** Multiplying 400 by 0.05 is the same as finding 5% of 400, which equals 20. **Final answer:** $$20$$