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NOTE.— As half a mile is equal to 4 furlongs, we add them to the 1 furlong, which make 5 furlongs. And as half a foot is equal to 6 inches, we add them to the 7 inches, which make 13 inches ; and these are equal to 1 foot 1 inch. By the same method, we obtain the result in the 14th and 17th questions.
in. 1 2
Note. - We divide the sum of the signs, in these questions, by 12, and write down the remainder, because it is Circular Motion.
COMPOUND SUBTRACTION teaches to find the difference be. tween two numbers of different denominations.
Write the smaller compound number under the greater, in the order of the different denominations, as pounds under pounds, shillings under shillings, fc. Begin with the lowest denomination and subtract each lower number from the one above it, and write the difference underneath. If, in any denomination, the lower number be greater than the one above it, add to the upper number the number required of this denomination to make one of the next higher; and, from the number thus obtained, subtract the lower number and set down the remainder underneath. Carry one to the next denomination in the subtrahend, and proceed in like manner with the subtraction, till the operation has been performed in all the columns, setting down the entire difference between the upper and lower numbers of the highest denomination, and the result will be the difference required.
NotE. — The reason for increasing the number of the minuend by the number required of a lower denomination to make one of the next higher, is precisely the same as that for which we add ten to a figure of the minuend, in Simple Subtraction. In both cases we add the number denoting the ratio between the denomination in question, and the next higher number of the minuend. In Simple Subtraction, the ratio of in- crease from right to left being uniformly tenfold, we add ten, while in the case of farthings, pence, and shillings, we add 4, 12, and 20.