Addends 1. 64 7 56 8 3672∞LO LO OD 49 39 27 ADDITION In adding a column, always look for combinations of two or more figures whose sum may be taken as an addend. Thus, in adding this column upward, say, "17, 27, 39, 49, 56, 64." In adding downward, say, "15, 25, etc." Few people find it worth while to combine three figures, except at the begin9 17 ning, as in adding this column downward, when we see at a glance that the 64 Sum sum of the first three figures is 15. 8 Add the following columns up and down, making com TO THE TEACHER: Give much blackboard practice with single columns like these. In pointing, for individual or concert work with the class, run the pointer from bottom to top (or reverse) of a column by a continuous motion. Do not move the pointer from one figure to another, stopping each time. Point thus for individuals, letting class make corrections. Encourage children to run up and down columns with a pencil, gradually increasing their speed. Add, and test your work by adding downward: 15. Four thousand thirty; sixteen thousand two hundred forty-nine; ten thousand four hundred eighty-six; three hundred ninety-eight thousand fifty; eight hundred thousand seven hundred sixty-nine; sixty thousand seventy. 16. Five million, three hundred eighty-nine thousand, seventy-seven; ninety million, eight hundred six thousand, seventy-six; ninety thousand; three hundred fortynine million; eighty-eight thousand thirty. Addition without a Pencil Everybody ought to be able to add two numbers of two figures each, without using a pencil. Here is an easy way: 43. 18 boys and 23 girls are how many pupils? 44. 39 boxes of Pippins and 56 boxes of Jonathans are how many boxes of apples? 45. Julian had 40 cents in his pocket and 93 cents in the bank. How much money had he? 46. Let each member of the class give two numbers for the next pupil to add, after adding those given him. SUBTRACTION 1. Mr. King had $8500 in the bank, and drew out $6937. How much had he left? The third method, called the Austrian, is gaining in use. = 3; 4 from 10 = 6; 10 from = 10; 4 and 6 = 10; 10 and To avoid confusion in problem work, we must remember that subtraction is taking away. Since the difference is always the number that must be added to the subtrahend to make the minuend, it follows that subtraction may be tested by adding the subtrahend and difference. If the sum obtained is the minuend, the work is correct. Subtraction without a Pencil Everybody should be able to subtract numbers of two figures each without using a pencil. Here is an easy way: From 83 take 57. 83-50=33. 33-7=26. Ans. Say 83, 33, 26. NOTE. This is not the "making change" method, for in making change we do not compute the amount received. 31. How much change is due in each case if one dollar is offered in payment for each of these purchases: 39¢; 48; 62; 796; 336; 29; 87; 62¢? 32. The sum of two numbers is 87. One of them is 49. What is the other? 33. What must be added to 45 to make 91? 34. What is gained by buying cloth at 47¢ a yard and selling it at 75¢ a yard? 35. John's heart beat 78 times a minute when he was well, but 130 times a minute during a severe illness. How much faster did the heart beat during illness than in health? |