1. The problem asks: If the decimal moves three places to the left, which operation does that represent and why? 2. When the decimal point moves to the left, the value of the number decreases by a factor of 10 for each place it moves. 3. Moving the decimal three places to the left means dividing the number by $10^3 = 1000$. 4. Therefore, the operation is division, because dividing by 1000 shifts the decimal three places left, making the number's value 1000 times less. 5. The other options are incorrect because: - Addition and subtraction shift the decimal point only when adding or subtracting multiples of powers of 10, but they do not inherently shift the decimal point. - Multiplication by 1000 shifts the decimal point three places to the right, increasing the number's value. Final answer: Division, because the decimal shifts left when you divide, making the number's value 1000 times less.