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Column Addition Addition Column addition allows people to work with the place-value columns in any order. It also allows them to write both digits of each partial answer directly underneath the appropriate column and then, if necessary, to go back and adjust the partial answers to find the final answer. Many students find this algorithm very natural—and instructive. Build Understanding Using page 13, explain that with this method of adding, students will add the digits in each column in any order, write individual place-value answers as they go, and then, if necessary, go back and adjust those partial answers to find the final answer. Use questions like the following to guide students through the examples: • Which two numbers will you begin with? (It doesn’t matter. The columns can be added in any order.) • Where do you write the sum for each column? (in the same column directly beneath the digits being added) • How do you adjust the place-value answers? (If the sum in a column has two digits, write down the ones digit and add a 1 to the answer in the column to the left.) While working through Example 1, model appropriate place-value language: “2 hundreds plus 4 hundreds are 6 hundreds; 6 tens plus 8 tens are 14 tens; and 8 ones plus 3 ones are 11 ones. ... Now, we have 14 tens and since 10 tens equal 1 hundred, we have 7 hundreds and 4 tens. ... We have 11 ones and since 10 ones equal 1 ten, we have 5 tens and 1 one.” (When working through Example 2, point out that another name for “14 hundreds” is “1 thousand, 4 hundreds.”) Page 13 Answer Key Check Understanding 1. 1,275 Make sure students understand that the final sum in Example 1 is 751. If necessary, work through additional examples on the board. When you are reasonably certain that most of your students understand the algorithm, assign the “Check Your Understanding ” exercises at the bottom of page 13. (See answers in margin.) 2. 821 3. 582 4. 913 5. 1,082 Copyright © Wright Group/McGraw-Hill Error Alert To help students organize both their thinking and their writing, encourage them to put extra space between the digits in each addend and to draw vertical lines to separate the place-value columns. 6. 1,152 7. 2,626 8. 8,348 12 Teacher Notes EM3_ALRH_Part 1_004-082_PDF.indd12 12 9/15/08 PDF Pages 2:44:48 PM Name Date Time Column Addition 2 +4 Example 1 Add the digits in each column. If necessary, adjust the hundreds and the tens. If necessary, adjust the tens and the ones. → → → 6 7 7 9 +4 Example 2 Copyright © Wright Group/McGraw-Hill Add the digits in each column. If necessary, adjust the hundreds and the tens. If necessary, adjust the tens and the ones. → → → 6 8 Addition Add one place-value column at a time. Write each place-value answer directly beneath the problem. Then go back and adjust each place-value answer, if necessary, one column at a time. 8 3 14 11 4 11 5 1 6 9 7 5 13 15 12 14 5 12 1, 4 6 2 Check Your Understanding Solve the following problems. 1. 511 + 764 2. 703 + 118 3. 303 + 279 4. 442 + 471 5. 453 + 629 6. 862 + 290 7. 1,859 + 767 8. 1,095 + 2,817 + 4,436 Write your answers on a separate sheet of paper. EM3_ALRH_Part 1_004-082_PDF.indd13 13 Student Practice 13 9/15/08 PDF Pages 2:44:48 PM