DIVISION OF FRACTIONS.
Rule.—Prepare the fractions, as for multiplication; then divide the numerator by the numerator, and the denominator by the denominator, if they will exactly divide; but if they will not do so, then invert the terms of the divisor, and multiply the dividend by it, as in multiplication.
Example.—Divide 9 16 by 4½.
9 16 ÷ (4½ or) 9 2 = ⅛ Answer.
RULE OF THREE IN FRACTIONS.
Rule.—State the terms, as directed in “Simple proportion;” reduce them (if necessary) to improper, or simple fractions, and the two first to the same denomination. Then multiply together the second and third terms, and the first with its parts inverted, as in division, for the answer.
Example.—If 4⅕ cwt. of sugar cost £19⅞, how much may be bought for £59⅝?
As 19⅞ : 59⅝ :: 4⅕
Or, 159 8 : 477 8 :: 21 5 : 12⅗ Answer.
8 159 × 477 8 × 21 5 = 80136 6360 = 12⅗ cwt.
DECIMALS.
A decimal fraction is that which has for its denominator an unit (1), with as many ciphers annexed as the numerator has places; and it is usually expressed by setting down the numerator only, with a point before it, on the left hand. Thus, 5 10 is ·5; 25 100 is ·25; 25 1000 is ·025; ciphers being prefixed, to make up as many places as are required by the ciphers in the denominator.