COPYING AND ADDING WITH CARRYING 97 76. Adding with Carrying. (WRITTEN WORK.) Add the examples below. Check your work. You should get every answer correct. It will save time if you add without copying. NEW WORK 77. Further Study of Carrying in Addition. (CLASS WORK.) There is nothing really new in this article, but there are some little "tricks" about carrying that you ought to be sure you know how to work. Watch for these "tricks" so that you won't get caught on one of them. Read carefully, but do not be too slow. FIRST TRICK In examples like Example (4) below, with a zero in the ones' place in the answer, pupils sometimes make mistakes. Answer the questions about Example (4). (A) 32 4 21 23 80 (a) What is the sum of the numbers in the ones' column? (b) What number is written under the ones' column? (c) What number is carried and added into the tens' column? Some pupils think that because the sum of the ones' column is 10, they should write the 1 and forget the 0. You won't make this mistake, will you? Look at the examples below and tell what to write in the ones' place in the answer and what to carry. CARRYING IN ADDITION Always write the ones under the ones' column and carry the tens into the tens' column. 99 SECOND TRICK The answer to Example (B) is different from any that you have had for addition. Study it carefully and answer the questions asked about it. (B) 22 61 43 126 (a) Can you tell two ways in which the answer for Example (B) is different from the answer for Example (A) on page 98? (b) Do you have to carry to get the answer in Example (B)? (c) Tell why there are three figures in the answer. In Example (B), John Baynes forgot and carried a 1 into the tens' column. Was his answer right? What do you think John got for his answer? John took a quick test one day, and he made other mistakes. Sometimes he forgot to "carry." Below is the test, with his answers. Some of the answers are right and some are wrong. Find the answers that are wrong and be ready to tell what John's mistakes were. Check your work. THIRD TRICK Look at the sum in Example (B) on page 99. It has three figures in the sum. The three figures are 1, 2, 6. The sum in Example (C) below also has three figures, but the center figure is zero. Don't let an example like this catch you. (C) 24 35 48 107 (a) What is the sum of the ones? (b) Tell why the zero is in this sum of the example. FOURTH TRICK The answer is not given for Example (D) below. Can you find out what the answer is? (D) 64 80 56 (a) Put a piece of paper under Example (D) and add. (b) What is the first figure you write down? (c) What is the sum? How many zeros in the sum? Be careful in examples like (D) with two zeros in the sum. (E) 48 39 56 43 176 FIFTH TRICK Can you do Example (E) without making any mistakes? Try it. (a) What is the sum of the ones? (b) What number is carried and added into the tens' column? (c) Is 176 the correct sum? REVIEW OF ADDITION WITH CARRYING 101 Be careful in adding examples like (E). The sum of the ones is 26. Write the 6 and carry the 2. Can you answer the questions below? 1. How many tens in 26? 2. How many ones in 26? 3. In Example (E) under what column does the 6 of the 26 belong? 4. What becomes of the 2 of the 26? Remember to write the ones under the ones' column. 78. Review of Addition with Carrying. (ORAL WORK.) In the example at the right the sum of the ones is 24. In adding the column we write 4 and carry the 2. If the sum of the ones in an example is 15, we write 5 and carry the 1. 29 17 If the sum of the ones in an example is 34, 18 we write 4 and carry the 3. Think of the following numbers as sums of the ones in addition examples and tell what you would write and carry. In Example 1 you should say, "Write zero and carry 2." |