1. The problem is to evaluate the expression $1 - 0.20 \times 800 = 0.80 \times 800 = 1000$.\n\n2. First, understand that multiplication and subtraction are involved. The expression can be interpreted as subtracting 20% of 800 from 1, then multiplying by 800, or as multiplying 0.80 by 800.\n\n3. Calculate $0.20 \times 800$ to find 20% of 800.\n$$0.20 \times 800 = 160$$\n\n4. Subtract this from 1 (if the original expression is $1 - 0.20$ times 800, it seems to be a misinterpretation; likely the intended operation is $0.80 \times 800$).\n\n5. Multiply $0.80 \times 800$ to get the final result.\n$$0.80 \times 800 = 640$$\n\n6. The final answer is $640$.\n\nNote: The original message seems to have a typo or confusion in the expression. If the goal is to find 80% of 800, the answer is $640$, not $1000$.