Reduction of common fractions to decimals. 1. How many tenths are there in ? in ? or; or fo This topic is continued on page 244 after division of decimals. Since cents are written as decimals of $1, in decimals, addition, subtraction, multiplication, and division are performed just as in United States money. Also since decimals are really fractions in another form, the principles of fractions are employed in explaining work in decimals. 1. How ADDITION OF DECIMALS many tenths are +16? .3+.1? 23 2. How many hundredths are 100+130? .07+.23? how many tenths? Add: Written Exercises 1. $4.36 2. $2.38 3. $4.22 4. $16.47 5. $71.16 7.92 8.45 9.06 8.33 6. Find the sum of 1.125, 4.27, and 6.075. 24.62 Write the units in one column, the tenths in another, in a column. Add and place the decimal point in the sum directly under the other decimal points. The sum is 11.470, but since (p. 227) .470 = .47, we write 11.47. 1.125 4.27 6.075 and so on. 11.47 Add columns; rows; the sums of columns; of rows: 41. 3.6+.38 +9.24 +58.9+.675+7.975 51. There are 5.875 cords of wood in one pile and 12.25 cords in another. How many cords are there in both piles? 52. A horse was fed daily 13 lb. of oats, 6.5 lb. of hay, and 8.25 lb. of straw. Find the weight of his daily food. 53. Edward rode 439.4 miles on the train in going from New York to Buffalo, and 535.9 miles in going from Buffalo to Chicago. How many miles did he ride? 54. At one time Minnesota produced .4 of the iron ore of this country, Michigan .25, and Alabama .125. What part of the country's output was produced by these states? 55. Add seventy and six tenths; forty-five and nine hundredths; six hundred and sixteen hundredths. 56. A chimney stands 220.25 ft. above ground and extends 18.5 ft. below, where it rests on a foundation 7.75 ft. deep. Find the total height of chimney and foundation. 57. A ball was thrown from the home plate to second base, 127.28 ft.; thence to first base, 90 ft.; then from first base to third base, 127.28 ft. How far did the ball travel? 58. Add: four hundred fifty-six; four hundred and fifty-six thousandths; nine thousand and ninety-five hundredths; eighty-six and eighty-six thousandths. 59. For six months one year, the rainfall in a certain place was: 4.09 in., 2.26 in., 5.49 in., .62 in., 5.03 in., and 1.86 in. Find the total rainfall for those months. 60. The Times Building extends 143 ft. along Broadway, 58.33 ft. along 42d Street, 137.833 ft. along 7th Avenue, and 20 ft. along 43d Street. Find the distance around it. SUBTRACTION OF DECIMALS .34-.04? 1. How many tenths are? .7-.3? .9-.4 ? 2. How many hundredths are 340-100? how many tenths? Subtract: Written Exercises 1. $8.35 2. $6.43 3. $8.44 4. $38.00 5. $68.14 6.82 Write the numbers so that the decimal points are in a column. 2.25 4.57 Subtract and place the decimal point in the difference directly under the other decimal points. Subtract as indicated: 7. 45.6-27.4 9. 3.48 2.57 8. 53.2-13.8 10. 8.06-5.28 13. From 100 subtract 24.58. 100 11. 6.325-4.146 12. 9.218-5.326 The decimal point is assumed to follow all integers. Without writing them we may consider 0's to occupy tenths' and hundredths' places of the minuend. |