Exercises upon the Table. 22. a. What places are occupied by the units' group? the thousands' group? the millions'? billions'? trillions'? b. Write 265 as units; as thousands; as millions. In reading and writing large numbers, the first thought should be of the groups. 23. To read integral numbers. Illustrative Example. Read the number 46372509. (1) Beginning at the right, point off the figures into groups of three figures each, thus: 46,372,509. (2) Beginning at the left, name the number expressed by each group in order, thus: "Forty-six million three hundred seventy-two thousand five hundred nine." NOTE. In reading any number, the pupil should make a slight pause after naming a group. The name of the units' group is omitted in reading. 25. To write integral numbers. Illustrative Example. Write in figures four hundred forty-seven million one hundred ninety-eight thousand six hundred ninety-four. (1) Think of the groups. These are 447 millions, 198 thousands, 694 units. (2) Arrange the groups in their proper order, thus: 447,198,694. Exercises. 26. Write in figures the following, supplying vacant places with zeros: 40. Seven thousand three hundred forty-one. 41. Eighteen thousand nine hundred eighty-four. 42. Thirty-seven thousand three hundred nineteen. 43. Nine hundred thousand five hundred sixteen. 44. Four hundred twenty thousand six hundred eighty. 45. Eight hundred ten thousand two hundred seven. 46. Two hundred fifty-nine thousand seventy. 47. One million one hundred thousand one hundred one. 48. Five million thirty-six thousand six hundred ten. 49. Forty-five million seven hundred twenty-four thou sand two hundred forty-seven. 50. Eighty million seventy thousand five hundred seven. 51. Nine hundred one million two hundred eighteen thousand five hundred twenty-two. 52. Three billion thirty-seven million nine hundred six thousand two hundred. 53. Two hundred thirty-four million eight hundred sixtythree thousand three hundred eighty-nine. 54. Seventeen billion seven hundred fifty-nine million ninety thousand sixty-seven. DECIMAL FRACTIONS. 27. As a hundred is made up of ten equal parts, each of which is a ten, and as a ten is made up of ten equal parts, each of which is one, so we may consider one to be made up of ten equal parts, each of which is a tenth; a tenth to be made up of ten equal parts, each of which is a hundredth; a hundredth to be made up of ten equal parts, each of which is a thousandth; and so on. Tenths, hundredths, thousandths, etc., are fractional units and, as they form a decimal scale (Art. 7), collections of such units are called decimal fractions. The above-named units are written as in the margin, each unit of a lower order being expressed by writing the figure 1, one place further to the right. One hundred, 100. 10. 1. 0.1 One hundredth, 0.01 28. The dot put at the right of the units' place is called the decimal point. NOTE. Even when not written, as when integers only are expressed, the decimal point is always understood to be at the right of the units' place. 29. The method of writing decimal fractions is shown by the following NOTE.-In writing decimal fractions it is well to fill the units' place with a zero when there is no other figure to be written there. 30. To read and write decimal fractions. Illustrative Examples. Read 0.063. First read the number as if it were an integral number, thus: "Sixty-three"; then add the name of the units of the lowest order (thousandths), thus, "Sixty-three thousandths." Write nine hundred sixty-three thousandths. First write the number as if it were an integral number, thus: 963, then place the decimal point so that the right-hand figure shall express the required denomination, thus, 0.963. To read or write integral numbers and decimals together, read or write first the integral number, then the decimal. In reading, use the word and before the decimal. Four ten-thousandths. 72. Twenty-seven thousandths. 73. 3 and 33 hundredths. 104 and 25 thousandths. 74. 7 and 29 thousandths. 45 hundred, and 5 tenths. 75. One hundred seventeen thousandths. 76. Four hundred and four ten-thousandths. 77. Six hundred seven, and sixty-seven thousandths. 78. Five hundred sixty-eight hundred-thousandths. 32. It is frequently convenient to separate a number into parts, each part containing only the units of a single order. Thus, the number 734.25 may be separated into 7 hundreds, 3 tens, 4 units, 2 tenths, and 5 hundredths. Such parts are called terms of the number. 1 UNITED STATES MONEY. 33. The units of United States money form a decimal scale, shown by the following 34. Dollars and cents are the units chiefly used in reckoning money. Cents are hundredths of a dollar. Dollars are written as integral numbers at the left of the decimal point; cents are written in the first two places at the right, and mills in the third place. The number 21 dollars, 43 cents, 8 mills is written thus: $21.438. The number 21 dollars, 5 cents, 3 mills is written thus: $21.053. 91. Fifteen dollars thirty-six cents. 92. Ninety-three dollars sixty-two cents five mills. 93. Seventeen dollars five mills. 94. Forty-five cents four mills. 95. Nine dollars five cents two mills. 96. Five hundred dollars five cents. 97. Nine thousand seventeen dollars two cents. 98. Sixty-eight thousand four hundred eighty dollars. |