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5. Hundreds. If we add one more to ninety-nine, we shall have ten tens, or one hundred. To express this, we write 1 in the third place. Hence
A figure standing in the third place expresses Hundreds. Thus,
100 is 10 tens, called one hundred.
234 is 2 hundreds, 3 tens, and 4 units, or two hundred and thirty-four.
999 is 9 hundreds, 9 tens, and 9 units, or nine hundred and ninety-nine.
1. Write neatly in figures the numbers from one hundred to one hundred and twenty-five; from two hundred and twentyfive to two hundred and fifty; from three hundred and fifty to three hundred and seventy-five; from four hundred and seventy-five to five hundred.
6. Periods. For convenience in reading and writing numbers the figures of a number are divided into periods of three places each. The first three places make the first or units period, the second three places make the second or thousands period, etc.
The first six periods are as follows:
The periods are separated from each other by commas.
EXERCISES ON THE TABLE.
1. Name the periods in order from units to quadrillions. 2. Name the places in order from units to quadrillions.
Name the following periods:
Write in figures—
44. Fifty-six thousand, four hundred.
45. Four million, two hundred and sixteen thousand, and one.
46. Forty million, forty thousand, and forty.
47. Six billion, six million, six thousand, and six.
48. Nine hundred and forty million, eight hundred and six thousand, four hundred and six.
49. Seven trillion, six billion, five million, four thousand, and three.
7. The table which has been given will enable us to read a number consisting of eighteen figures: the periods which follow them are
Quintillions, Sextillions, Septillions, Octillions, Nonillions, Decillions, Undecillions, Duodecillions, etc.
8. In this system seven letters are used to express numbers. Thus,
LETTERS, I, V, 5.
X, L, C. D, M, 10. 50. 100. 500. 1000.
Other numbers are expressed by writing two or more of these letters side by side.
(1) When a letter is repeated its value is repeated; thus, II represents 2; XXX, 30; CCCC, 400, etc.
(2) When a letter is placed before one of greater value, their Difference is expressed; thus, IV represents 4; XL, 40; XC, 90, etc.
(3) When a letter is placed after one of greater value, their Sum is expressed; thus, VI represents 6; XV, 15; LX, 60,
(4) A dash placed over a letter increases its value a thousand fold; thus, V represents 5000; VII, 7000; XI, 11000, etc.