Name Date Class LESSON Problem Solving 4-2 Adding and Subtracting Decimals Write the correct answer. 1. In the Pacific Ocean, the Philippine 2. Hawaii’s Mauna Kea measures Trench is 10.047 kilometers deep. In 9.754 kilometers from its base to its the Atlantic Ocean, the Brazil Basin peak. The base of Mauna Kea lies is 6.119 kilometers deep. How much 5.549 kilometers below the ocean. deeper is the Philippine Trench than What is the height of the part of the Brazil Basin? Mauna Kea that is above sea level? 3. A team of mountain climbers makes 4. At dawn, the temperature at the .camp 1.48 kilometers above sea summit of a mountain was ؊8.5°C level. They climb another By noon, the temperature had 2.91 kilometers to the mountain’s increased 3.6°C. What was the peak. How tall is the mountain? temperature at noon? Choose the letter for the best answer. This table gives the heights of the tallest 5. In 2000, Joby Ogwyn became the mountains on each of the seven youngest person to climb each of the continents. seven summits. How much higher did he climb on Vinson Massif than on The Seven Summits Puncak Jaya? Height A 0.013 km C 0.181 km Mountain Country (km) B 0.097 km D 4.888 km Nepal- Mt. Everest Tibet 8.848 6. Mt. Kilimanjaro, Mt. Elbrus, and Mt. Aconcagua were the first three of Mt. Aconcagua Argentina 6.960 the seven summits Joby climbed. United What was the total height he Mt. McKinley States 6.194 climbed? Mt. Kilimanjaro Tanzania 5.896 F 18.498 km H 21.45 km Mt. Elbrus Russia 5.642 G 25.458 km J 19.164 km Vinson Massif Antartica 4.897 New 7. Mt. Aconcagua is about 1.3 kilometers Puncak Jaya Guinea 4.884 taller than which mountain? A Mt. Everest C Mt. McKinley B Mt. Elbrus D Vinson Massif Copyright © by Holt, Rinehart and Winston. All rights reserved. 22 Holt Middle School Math Course 2 LESSON Practice C LESSON Reteach 4-2 Adding and Subtracting Decimals 4-2 Adding and Subtracting Decimals Add or subtract. Estimate to check whether your answer is You can use a place-value chart to add decimals. reasonable. Add: 3.48 ؉ 2.7 Subtract: 68 ؊ 5.9 ؉ ؊ ؉ 1. 8.326 8.49 2. 13.845 10.87 3. 42.35 4.368 Step 1: Line up the decimal points. Step 1: Line up the decimal points. 16.816 2.975 46.718 Use 0 as a placeholder for Use 0 as a placeholder for hundredths in 2.7. tenths in 68. ؊ 7.52 5. ؊5.421 ؉ 18.4 6. ؊12.54 ؊ 16.951 8.695 .4 Ones . Tenths Hundredths Tens Ones . Tenths ؊29.491 12.979 1.175 ؊ 9.458 8. 8.552 ؉ 14.84 9. ؊75.25 ؉ (؊6.382) 3 . 48 68. 0 6.742 .7 ؊2.716 23.392 ؊81.632 ؉ 2 . 70 ؊ 5 . 9 (؊ 9.654 11. ؊38.59 ؊ (؊7.816) 12. 9.561 ؉ (؊16.82 47.68 .10 Step 2: Add. Place the decimal point Step 2: Subtract. Place the decimal .؊30.774 ؊7.259 in the answer. point in the answer 38.026 ؉ 6.357 14. 123.45 ؊ 12.345 15. 6.456 ؉ (؊87.51) Ones . Tenths Hundredths Tens Ones . Tenths 18.234 .13 ؊81.054 1 710 111.105 24.591 3 . 48 68. 0 ؊ ؊ ؉ ؊ ؉ 2 . 70 ؊ 5 . 9 (45.846 ) 82.64 .18 59.162 95.216 .17 56.842 74.832 .16 17.99 36.054 36.794 6 . 18 62. 1 .62 ؍ ؉ 19.17 ؉ 8.357 20. 12.63 ؉ 72.029 ؉ 5.9 Step 3: Estimate: 3 ؉ 3 = 6. Step 3: Estimate to check: 68 ؊ 6 27.205 .19 54.732 90.559 So, 6.18 is a reasonable answer. So, 62.1 is a reasonable answer. .؉ 56.27 ؊ 13.02 ؊ 25.821 22. 9.30 ؉ 17.43 ؉ 38.57 ؊ 25.719 Add or subtract. Estimate to check your answer 49.408 .21 ؉ 8.45 2. 9.36 ؊ 7.29 19.67 .1 39.581 66.837 23. A whippet can run a 200-yard course at a rate of 35.5 mi/h. Tens Ones . Tenths Hundredths Tens Ones . Tenths Hundredths This is 3.85 mi/h slower than the top speed of a greyhound. 19. 67 9 . 36 How fast can a greyhound run? ؉ 8 . 45؊ 7 . 29 39.35 mi/h 28. 12 2 . 07 ؊ ؉ 24. Heike has 2 rocks. If the total weight of both rocks is 3. 25.36 9.7 4. 12.89 37.07 54.283 kilograms and the first rock weighs 29.928 kilograms, Tens Ones . Tenths Hundredths Tens Ones . Tenths Hundredths how much does the second rock weigh? 25. 36 12. 89 kilograms ؊ 9 . 7 0 ؉ 37. 07 24.355 15. 66 49. 96 (؉ 9.19 6. 57.06 ؊ 27.38 7. 48.3 ؉ (؊10.73 34.71 .5 43.9 29.68 37.57 Copyright © by Holt, Rinehart and Winston. Copyright © by Holt, Rinehart and Winston. All rights reserved. 19 Holt Middle School Math Course 2 All rights reserved. 20 Holt Middle School Math Course 2 LESSON Challenge LESSON Problem Solving 4-2 Answer Match 4-2 Adding and Subtracting Decimals Add or subtract. Draw lines to match equivalent answers in Write the correct answer. each column. Each answer in the middle column matches an 1. In the Pacific Ocean, the Philippine 2. Hawaii’s Mauna Kea measures answer in both outside columns. Trench is 10.047 kilometers deep. In 9.754 kilometers from its base to its the Atlantic Ocean, the Brazil Basin peak. The base of Mauna Kea lies ؊61.244 ؉ 59.014 2. 21.65 ؉ 14.2 ؉ 10.03 3. 41.729 ؉ 14.92 .1 is 6.119 kilometers deep. How much 5.549 kilometers below the ocean. ؊2.23 45.88 59.649 deeper is the Philippine Trench than What is the height of the part of the Brazil Basin? Mauna Kea that is above sea level? ؉ 7.052 5. 212.8 ؊ 136.2 6. 42.25 ؊ 13.174 3.928 kilometers 4.205 kilometers 4.018 .4 11.07 76.6 29.076 3. A team of mountain climbers makes 4. At dawn, the temperature at the .camp 1.48 kilometers above sea summit of a mountain was ؊8.5°C level. They climb another By noon, the temperature had ؊104.02 ؉ 149.9 8. 0.015 ؊ 6.72 9. ؊0.673 ؉ (؊5.707) 2.91 kilometers to the mountain’s increased 3.6°C. What was the .7 ?؊6.705 ؊6.38 peak. How tall is the mountain? temperature at noon 45.88 kilometers ؊4.9°C 4.39 ؊5.23 ؊ 0.804 ؉ 35.11 11. ؊70.6 ؉ 48.05 ؉ 33.62 12. 22.015 ؉ 23.865 .10 29.076 11.07 45.88 Choose the letter for the best answer. This table gives the heights of the tallest 5. In 2000, Joby Ogwyn became the mountains on each of the seven youngest person to climb each of the ؊ ؊ ؊ 13. 60.25 0.601 14. 65.109 5.46 15. 7.17 9.4 continents. seven summits. How much higher did ؊2.23 he climb on Vinson Massif than on 59.649 59.649 The Seven Summits Puncak Jaya? Height ࠗA 0.013 km C 0.181 km ؊ ؉ ؊ ؊ ؊ ؉ ؉ 16. 1.08 3.797 9.422 17. 10.25 12.03 0.45 18. 16.02 44.48 16.1 Mountain Country (km) B 0.097 km D 4.888 km -؊6.705 ؊2.23 76.6 Nepal Mt. Everest Tibet 8.848 6. Mt. Kilimanjaro, Mt. Elbrus, and Mt. Aconcagua were the first three of Mt. Aconcagua Argentina 6.960 .؉ 4.03 ؉ 17.706 20. 130.82 ؊ 101.744 21. ؊5.61 ؊ 1.095 the seven summits Joby climbed 15.25 .19 United ؊6.705 What was the total height he 29.076 36.986 Mt. McKinley States 6.194 climbed? Mt. Kilimanjaro Tanzania 5.896 ࠗF 18.498 km H 21.45 km ؊ 21.1 ؉ 3.029 23. 45.006 ؉ (؊8.02) 24. 52.73 ؊ 53.71 ؉ 12.05 Mt. Elbrus Russia 5.642 G 25.458 km J 19.164 km 11.691 .22 ؊6.38 36.986 11.07 Vinson Massif Antartica 4.897 New 7. Mt. Aconcagua is about 1.3 kilometers Puncak Jaya Guinea 4.884 taller than which mountain? ؊33.42 ؊ (؊110.02) 26. 46.01 ؉ 9.9 ؊ 62.29 27. 6.007 ؉ 74.2 ؊ 43.221 A Mt. Everest C Mt. McKinley .25 ؊6.38 36.986 ࠗB Mt. Elbrus D Vinson Massif 76.6 Copyright © by Holt, Rinehart and Winston. Copyright © by Holt, Rinehart and Winston. All rights reserved. 21 Holt Middle School Math Course 2 All rights reserved. 22 Holt Middle School Math Course 2 Copyright © by Holt, Rinehart and Winston. All rights reserved. 131 Holt Middle School Math Course 2.