60. Addition and Subtraction of United States Money What is the sum of $4.20 and $2.248? What is their difference? 1. In writing sums of money for addition and subtraction, how should the numbers be placed with reference to the decimal points? Why is this done? 2. How many places are pointed off in an answer, in adding or subtracting sums of money in which mills occur? [With pencil.] Add: 3. $2.84, $3.145, $4.025, $1.038, $2.75. 4. $.028, $.085, $.25, $.78, $.052. 5. $0.125, $0.375, $5.87, $8.42. 6. $4.85, $6.375, $5.00, 75¢, $.875, $.625. 7. $0.60, 98¢, $0.25, $0.178, $1.25, $8. Subtract: 8. $1.25 from $5.00. 9. $2.98 from $10.00. 10. 95¢ from $2. 11. $.025 from $.048. 14. $.015 from $.20. 15. $.003 from 3¢. 16. $.075 from 10¢. 61. Multiplication of United States Money How much must be paid for 9 yards of muslin at $.15 a yard? 1. In the solutions above, how many places were pointed off in the first product? In the second product? Since it is not possible to pay with coins a sum of money less than a cent, it is customary to call any number of mills from 5 mills to 9, a full cent. In paying a bill for $1.125, the amount given is $1.13. Four mills or less are not counted. For example, $.044 is called $.04, and $2.023 is called $2.02. [With pencil.] 2. At $.065 a foot, how much must be paid for 7 feet of picture molding? 3. Closet hooks are selling at $.025 apiece. How much must be paid for 15 hooks? DIVISION OF UNITED STATES MONEY 4. Coat hangers are selling at $.075 apiece. 93 Find the cost of 9. 1. In finding of $9.12, how many places were pointed off in the quotient for cents? 2. In finding of $6.075,, how many places were pointed off in the quotient? Why? [Use pencil only when needed.] 3. Three boys buy a rowboat for $30.75, sharing the expense equally. Find how much each boy has to pay. 4. A Christmas present of $5.50 is divided equally between two sisters. How much is given to each? 5. Margaret buys of a yard of velvet at $5.49 a yard and 13 yards of lining at $.375 a yard. How much does she owe the merchant? II How can you find how many times 25 cents is contained in $1.00? 5 cents in $1.25? In dividing one sum of money by another, it is necessary to express both sums as like quantities. In dividing 1 dollar by 25 cents, we divide either 100 cents by 25 cents, or $1 by $. In dividing $1.25 by 5 cents, we divide either 125 cents by 5 cents, or $1.25 (110 dollars) by $.05 (150 dollars). At 75¢ apiece, how many library books can be bought for $30? $30 ÷ 75¢ = $30.00 ÷ $.75. Notice that, in dividing $30 by 754, the numbers are both written with a dollar sign and with two figures at the right of the decimal point. Why is this done? In what other way might the two sums of money have been written? [With pencil.] 1. Express as like quantities: $2.25 and 25¢; 68¢ and $4; 45¢ and $5; $5.25 and 8e; 42¢ and $20. First express as like quantities, and then divide: 1. A phonograph is advertised for sale for $35. At the rate of 25¢ a day, how many days will it take to save money enough to buy it? 2. Find the length of time required, at the rate of 5¢ a day, to save $2.25. To save $4. 3. Robert has saved $4.25 toward the cost of a work bench with a set of tools advertised for sale for $22.25. At the rate of 75¢ a week, how many weeks will it take him to save the rest of the money? BOYS AND GIRLS IN BUSINESS 95 4. Helen wishes to save $6 for the expenses of a trip to her aunt's. How many more weeks will it take her to save the money at the rate of 25¢ a week than at the rate of 75¢ a week? 5. Think of something that you would like to buy. Find out its price, and then find how long it would be before you could buy it if you were to save 15¢ a week. 6. Make and solve two other problems about saving money. 1. Robert and Helen had a lemonade stand. They bought 11 dozen lemons at the rate of 5¢ apiece, 5 pounds of sugar at $.11 a pound, and 1 cake of ice at 10¢; then they made 12 quarts of lemonade, which they sold at 5¢ a glass. A glass holds pint. How much did they receive for their lemonade? What was their profit? 2. Fred Martin and three of his friends decided to buy a radiopticon. They planned to earn money for it by giving three evening entertainments, using a magic lantern. The boys bought dozen lantern slides at $1.75 a dozen, and spent 8¢ for oil, 10¢ for tickets, and 50¢ to have their tent repaired. How much money did the boys spend? |