1. The problem is to round decimal numbers to the nearest thousandth. 2. The rule for rounding to the nearest thousandth is to look at the digit in the ten-thousandth place (the fourth digit after the decimal point). 3. If this digit is 5 or greater, increase the thousandth digit by 1. 4. If this digit is less than 5, keep the thousandth digit the same. 5. Apply this rule to each number: **First set:** 1) 6.6368: The ten-thousandth digit is 8 (>=5), so round up the thousandth digit 6 to 7. Result: 6.637 2) 2.7978: Ten-thousandth digit 8 (>=5), round up 7 to 8. Result: 2.798 3) 4.6435: Ten-thousandth digit 5 (>=5), round up 3 to 4. Result: 4.644 4) 5.6931: Ten-thousandth digit 1 (<5), keep 3. Result: 5.693 5) 1.9555: Ten-thousandth digit 5 (>=5), round up 5 to 6. Result: 1.956 **Second set:** 1) 7.92699: Ten-thousandth digit 9 (>=5), round up 6 to 7. Result: 7.927 2) 3.94863: Ten-thousandth digit 6 (>=5), round up 8 to 9. Result: 3.949 3) 8.74583: Ten-thousandth digit 8 (>=5), round up 5 to 6. Result: 8.746 4) 3.59762: Ten-thousandth digit 6 (>=5), round up 7 to 8. Result: 3.598 5) 8.65114: Ten-thousandth digit 1 (<5), keep 1. Result: 8.651 6) 3.17121: Ten-thousandth digit 2 (<5), keep 1. Result: 3.171 7) 3.98549: Ten-thousandth digit 4 (<5), keep 5. Result: 3.985 8) 8.14534: Ten-thousandth digit 3 (<5), keep 5. Result: 8.145 9) 9.23179: Ten-thousandth digit 7 (>=5), round up 1 to 2. Result: 9.232 10) 3.75649: Ten-thousandth digit 4 (<5), keep 6. Result: 3.756