OPERATION. '125) '00375('03 375 000 The divisor, 125, in 375 goes 3 times, and no remainder. We have only to place the decimal point in the quotient, and the work is done. There are five decimal places in the dividend; consequently there must be five in the divisor and quotient counted together; and, as there are three in the divisor, there must be two in the quotient; and, since we have but one figure in the quotient, the deficiency must be supplied by prefixing a cipher. The operation by vulgar fractions will bring us to the same result. Thus, '125 is 2, and 00375 is 100%: now, Too 100% = 13388880 To '03, the same as before. ¶ 73. The foregoing examples and remarks are sufficient to establish the following RULE. In the division of decimal fractions, divide as in whole numbers, and from the right hand of the quotient point off as many figures for decimals, as the decimal figures in the dividend exceed those in the divisor, and if there are not so many figures in the quotient, supply the deficiency by prefixing ciphers. If at any time there is a remainder, or if the decimal figures in the divisor exceed those in the dividend, ciphers may be annexed to the dividend or the remainder, and the quotient carried to any necessary degree of exactness; but the ciphers annexed must be counted so many decimals of the dividend. EXAMPLES FOR PRACTICE. 4. If $472'875 be divided equally between 13 men, how much will each one receive? Ans. $36'375. 5. At $75 per bushel, how many bushels of rye can be bought for $141 ? Ans. 188 bushels. 6. At 124 cents per lb., how many pounds of butter may be bought for $37? Ans. 296 lb. 7. At 6 cents apiece, how many oranges may be bought for $8? Ans. 128 oranges. 8. If '6 of a barrel of flour cost $5, what is that per barrel? 9. Divide 2 by 53'1. Ans. $8333 +. 10. Divide ‘012 by ‘005. Quot. 2'4. 11. Divide three thousandths by four hundredths. Quot. '075 12. Divide eighty-six tenths by ninety-four thousandths. 13. How many times is '17 contained in 8? REDUCTION OF COMMON OR VULGAR FRACTIONS TO DECIMALS. ¶ 74. 1. A man has of a barrel of flour; what is that expressed in decimal parts? As many times as the denominator of a fraction is contained in the numerator, so many whole ones are contained in the fraction. We can obtain no whole ones in , because the denominator is not contained in the numerator. We may, however, reduce the numerator to tenths, (¶ 72, ex. 2,) by annexing a cipher to it, (which, in effect, is multiplying it by 10,) making 40 tenths, or 4'0. Then, as many times as the denominator, 5, is contained in 40, so many tenths are contained in the fraction. 5 into 40 goes 8 times, and no remainder. Ans. '8 of a bushel. 2. Express of a dollar in decimal parts. The numerator, 3, reduced to tenths, is 38, 3'0, which, divided by the denominator, 4, the quotient is 7 tenths, and a remainder of 2. This remainder must now be reduced to hundredths by annexing another cipher, making 20 hundredths. Then, as many times as the denominator, 4, is contained in 20, so many hundredths also may be obtained. 4 into 20 goes 5 times, and no remainder. of a dollar, there fore, reduced to decimals, is 7 tenths and 5 hundredths, that is, '75 of a dollar. The operation may be presented in form as follows. Num. Denom. 4) 3'0 ("75 of a dollar, the Answer. 28 20 20 3. Reduce to a decimal fraction. The numerator must be reduced to hundredths, by annexing two ciphers, before the division can begin. 66) 4'00 (0606+, the Answer. 396 400 396 4 As there can be no tenths, a cipher must be placed in the quotient, in tenth's place. Note. cannot be reduced exactly; for, however long the division be continued, there will still be a remainder.* It is sufficiently exact for most purposes, if the decimal be extended to three or four places. From the foregoing examples we may deduce the following general RULE: To reduce a common to a decimal frac * Decimal figures, which continually repeat, like '06, in this exanple, are called Repetends, or Circulating Decimals. If only one figure repeats, as '3333 or 7777, &c., it is called a single repetend. If two or more figures circulate alternately, as '060606, '234234234, &c., it is called a compound repetend. If other figures arise before those which circulate, as 743333, 143010101, &c., the decimal is called a mixed repetend. A single repetend is denoted by writing only the circulating figure with a point over it: thus, '3, signifies that the 3 is to be continually repeated, forming an infinite or never-ending series of 3's. A compound repetend is denoted by a point over the first and last repeating figure: thus, 234 signifies that 234 is to be continually repeated. It may not be amiss, here to show how the value of any repetend may be found, or, in other words, how it may be reduced to its equivalent vulgar fraction. = If we attempt to reduce to a decimal, we obtain a continual repetition of the figure 1: thus, '11111, that is, the repetend 'i. The value of the repetend '1, then, is ; the value of 222, &c., the repetend '2, will evidently be twice as much, that is, . In the same manner, 3, and 4, and '5 = §, and so on to 9, 1. What is the value of '8? 2. What is the value of '6? Ans. §. of "? of '4? of '5? which =} = 1. Ans. & What is the value of "3? of '9? of ‹i ? If be reduced to a decimal, it produces '010101, or the repetend Ŏi, The repetend '02, being 2 times as much, must be and ‘03 — 9, and '48, being 48 times as much must be 38, and 74 = }}, &c. tion,-Annex one or more ciphers, as may be necessary, to the numerator, and divide it by the denominator. If then there be a remainder annex another cipher, and divide as before, and so continue so long as there shall continue to be a remainder, or until the fraction shall be reduced to any necessary degree of exactness The quotient will be the decimal required, which must consist of as many decimal places as there are ciphers annexed to the numerator; and, if there are not so many figures in the quotient, the deficiency must be supplied by prefixing ciphers. EXAMPLES FOR PRACTICE. 4. Reduce †,†, 4, and 2 to decimals. Ans. '5; 25; '025; '00797 + 5. Reduce, Too, 175, and to decimals. Ans. '692; '003; '0028+; '000183 +. 6. Reduce 171, 167, 680 to decimals. 7. Reduce,, 585, 1, 3, 11, 1, 989 to decimals. 8. Reduce, , §, t, t, t, t, zb, 25, to decimals. If be reduced to a decimal, it produces '001; consequently, '002, and ‘037 9, and 425 = 3, &c. As this principle will apply to any number of places, we have this general RULE for reducing a circulating decimal to a vulgar fraction,—Make the given repetend the numerator, and the denominator will be as many 9s as there are repeating figures. 3. What is the vulgar fraction equivalent to '704? 4. What is the value of '003? 2463? -'002103? 5. What is the value of '43? 324? Ans. 8. 01021 ? 701 Ans. to last, 33335. In this fraction, the repetend begins in the second place, or place of hundredths. The first figure, 4, is fo, and the repetend, 3, is of To, that is, these two parts must be added together. + 3% = 38 18, Ans. Hence, to find the value of a mixed repetend,-Find the value of the two parts, separately, and add them together. 6. What is the value of 153? 7. What is the value of '0047? 8. What is the value of '138? 138 = 73%, Ans Ans. $30. It is plain, that circulates may be added, subtracted, multiplied, and divided, by first reducing them to their equivalent vulgar fractions. REDUCTION OF DECIMAL FRACTIONS. T75. Fractions, we have seen, (T 63,) like integers, are reduced from low to higher denominations by division, and from high to lower denominations by multiplication. To reduce the decimal of a To reduce a compound num-| ber to a decimal of the highest higher denomination to integers denomination. of lower denominations. 1. Reduce 7 s. 6 d. to the decimal of a pound. Ans. 2. Reduce 375 £. to integers of lower denominations. 375 £. reduced to shillings, 6 d. reduced to the decimal of a shilling, that is, divided that is, multiplied by 20, is by 12, is '5 s., which annexed 7'50 s.; then the fractional to the 7 s. making 7'5 s., and part, '50 s., reduced to pence, divided by 20, is 375 £. the that is, multiplied by 12, is 6 d. Ans. 7 s. 6 d. The process may be pre- That is,-Multiply the given sented in form of a rule, thus:- decimal by that number which Divide the lowest denomina- it takes of the next lower detion given, annexing to it one nomination to make one of this or more ciphers, as may be higher, and from the right necessary, by that number hand of the product point off which it takes of the same to as many figures for decimals make one of the next higher as there are figures in the denomination, and annex the given decimal, and so conquotient, as a decimal to that tinue to do through all the dehigher denomination; so con- nominations; the several numtinue to do, until the whole bers at the left hand of the shall be reduced to the deci- decimal points will be the mal required. EXAMPLES FOR PRACTICE. 3. Reduce 1 oz. 10 pwt. to the fraction of a pound. OPERATION. 20) 10'0 pwt. 12)1'5 oz. '125 lb. Ans. N value of the fraction in the proper denominations. EXAMPLES FOR PRACTICE. 4. Reduce '125 lbs. Troy to integers of lower denominations. lb. '125 OPERATION. 12 oz. 1'500 20 pwt. 10'000. Ans. Joz.10pwt. |