1. Problem: Round 0.007856 to 2 significant figures. Step 1: Identify the first 2 significant figures: 7 and 8. Step 2: Look at the next digit (5) to decide rounding. Step 3: Since the next digit is 5, round up the last significant figure. Step 4: Rounded value: 0.0079. 2. Problem: Round 45.783 to 3 significant figures. Step 1: First 3 significant figures: 4, 5, 7. Step 2: Next digit is 8, so round up. Step 3: Rounded value: 45.8. 3. Problem: Round 9984 to 2 significant figures. Step 1: First 2 significant figures: 9, 9. Step 2: Next digit is 8, round up. Step 3: Rounded value: 10000. 4. Problem: Round 0.56049 to 4 significant figures. Step 1: First 4 significant figures: 5, 6, 0, 4. Step 2: Next digit is 9, round up. Step 3: Rounded value: 0.5605. 5. Problem: Round 123.45 to 4 significant figures. Step 1: First 4 significant figures: 1, 2, 3, 4. Step 2: Next digit is 5, round up. Step 3: Rounded value: 123.5. 6. Problem: Round 7.999 × 10⁴ to 2 significant figures. Step 1: First 2 significant figures: 7, 9. Step 2: Next digit is 9, round up. Step 3: Rounded value: 8.0 × 10⁴. 7. Problem: Round 0.0032048 to 3 significant figures. Step 1: First 3 significant figures: 3, 2, 0. Step 2: Next digit is 4, no rounding up. Step 3: Rounded value: 0.00320. 8. Problem: Round 8765.2 to 3 significant figures. Step 1: First 3 significant figures: 8, 7, 6. Step 2: Next digit is 5, round up. Step 3: Rounded value: 8770. 9. Problem: Round 56.0501 to 4 significant figures. Step 1: First 4 significant figures: 5, 6, 0, 5. Step 2: Next digit is 0, no rounding up. Step 3: Rounded value: 56.05. 10. Problem: Round 2.4445 × 10⁻³ to 3 significant figures. Step 1: First 3 significant figures: 2, 4, 4. Step 2: Next digit is 5, round up. Step 3: Rounded value: 2.44 × 10⁻³. Final answers: 1. 0.0079 2. 45.8 3. 10000 4. 0.5605 5. 123.5 6. 8.0 × 10⁴ 7. 0.00320 8. 8770 9. 56.05 10. 2.44 × 10⁻³