COMPOUND SUBTRACTION. COMPOUND SUBTRACTION is the method of deducting one Compound Number from another. RULE.—1. Place the less number under the greater, in such a way that the numbers of the same denomination shall be below each other-pounds under pounds, shillings under shillings; and so on. 2. Beginning at the lowest denomination, subtract the under from the upper figures, and place the remainder directly below : then subtract the under from the upper figures of the next denomination; and so on with all the others, writing the remainders in each case below their respective denominations. The subtracting of the highest denomination is performed as in Simple Subtraction. 3. When the under number of any denomination is greater than the upper, add to the upper number the value of one of the next higher denomination, and then go on with the subtraction. As an equivalent, however, for this, the under figure of the next higher denomination must be considered as having had 1 added to it before it is deducted from the figure above, on the same principle as in Simple Subtraction. Example. From £36, 14s. 5£d. take £27, 178. 82d. Commencing at the lowest term, we have 3 t S. A. farthings to take from 2. but as we cannot do this. 36 14 57 we borrow from the pence l penny, or 4 farthings, 27 17 87 which, added to the 2 farthings, make 6; then 3 £8 16 83 from 6 and 3 remain, which are written under the farthings. We now repay the penny borrowed by carrying 1 to the 8 pence in the lower line; there is thus 9 pence to subtract from 5, but as this cannot be done, we borrow a shilling, or 12 pence, which, added to the 5, make 17, then 9 from 17 and 8 remains, which is placed under the pence. The borrowed shilling is repaid by adding 1 to the 17, making 18 to be taken from 14, but as we cannot do this, we borrow 1 pound, or 20s., which being added to 14, make 34; then 18 from 34 and 16 remain, which are placed under the shillings. The £1 borrowed is carried to the £27, which are subtracted, as in Simple Subtraction. Exercises in Money. 3. £35 14 51 £45 12 7 £315 10 62 £183 3 26 12 71 33 15 61 276 17 82 97 14 53 1. 2. COMPOUND MULTIPLICATION. COMPOUND MULTIPLICATION is the method of multiplying a compound number by a simple number. RULES. RULE.— 1. Write the multiplier below the right-hand figures of the multiplicand. 2. Multiply the lowest denomination of the latter by the multiplier; find how many of the next higher denomination is contained in the product, and carry the number of times to that denomination, writing any remainder below the number just multiplied. : 3. Multiply the next higher denomination in the same way, writing down any remainder, and carrying to the denomination above it, as before; and so on till all the denominations have been multiplied in succession : the highest denomination is multiplied as in Simple Multiplication. Example.-Multiply £37, 15s. 82d. by 6. £ $. d. Here the multiplier, 6, is placed under the pence 37 15 89 (the farthings being considered merely as a frac tion of the pence), and beginning with the farthings we have 6 times 3, which make 18 farthings, and £226 14 41 these being converted into pence, give 4. pence. The is placed under the farthings, and the 4 carried to the pence. Multiplying the pence, we have 6 times 8 making 48, and the 4 from the farthings make 52 pence, or 4 shillings and 4 pence. The 4d. is put under the pence, and the 4s. are carried to the shillings: then 6 times 15 are 90, and 4 are 94s. ; that is, 4 pounds and 14 shillings over. The 14s. are marked under the shillings, and the £4 carried to the pounds: then multiply the £37, as in Simple Multiplication, and include the £4 from the shillings; the product, 226, is written under the pounds. NOTE.-In multiplying the shillings, the following is the most convenient method :-First multiply the units, take the tens out of the product and carry them to the tens, writing any remainder below the units ; next multiply the tens, and having added those brought from the units, halve the product; carry the half to the pounds, and if there is a remainder of 1, write 1 below the tens; if there is no remainder, there is nothing written below the tens of the shillings. The halving of the product of the tens is merely a short way of dividing it by 20, to convert it into pounds. . In the above example we first multiply the units of the shillings-6 times 5 are 30, and 4 from the pence are 34: write 4 below the units, and carrying 3 to the tens, 6 times I are 6, and 3 are 9; then halving this, write the remainder, I, below the tens, and carry the half, 4, to the pounds, which are multiplied as before. II. WHEN THE MULTIPLIER IS THE PRODUCT OF TWO NUMBERS, NEITHER OF WHICH EXCEEDS 12. RULE. Find the factors or numbers that produce the multiplier, then multiply the given quantity by the one factor, and the product by the other : the last product is the answer. Examples.-Multiply £1, 2s. 6d. by 14. Here the multiplier, 14, is the product of the two numbers, 7 and 2; we therefore first 7 17 6 multiply the given sum by 7, and then the product by 2. £15 15 0 Ans. Exercises. 1. Multiply £0 2 6 by 15, . . Ans. £1 17 6 0 6 10 7 3 6 0 9 13 19 4 11 1 14. 108 16 11 119 16 3 72 6 9 120 17 4 567 0 0 8 15 41, 736 9 9 0 981 63 18 9 73 19 113, 4143 18 10 96 13 97 7831 15 52 67 1 31 108, 7242 19 6 81 14 103, 144, • 1 . 5 11771 0 wiaj si conicos o esc |