LEDGER ACCOUNTS.

123. The principal book of accounts among merchants is called a ledger. In it are brought together scattered items of accounts, often making long columns. As a rapid way of finding the amounts, accountants generally add more than one column at a single operation (Art. 48). The examples below may be added both by the usual method and by that which is more rapid.

COMPOUND NUMBERS.

124. A COMPOUND NUMBER is a collection of concrete units of different denominations; as, 5 pounds and 6 ounces; 4 feet and 5 inches.

125. A scale expresses the law of relation between the different units of a number.

The different units of simple numbers have a uniform tenfold increase from lower to higher orders, and a like decrease from higher to lower orders. They, therefore, are said to have a uniform scale.

In compound numbers, the names of different measuring units (Art. 9) are included in the expression of a single quantity, so that the relation of the units of one order to those of another is that of a varying scale; as in the expression of pounds, shillings, pence, and farthings, it is 4, 12, and 20.

REDUCTION OF COMPOUND NUMBERS.

126. REDUCTION is the process of changing numbers from one denomination to another, without altering their values. It is of two kinds, Reduction Descending and Reduction Ascending.

Reduction Descending is changing numbers of a higher denomination to a lower denomination; as pounds to shillings, &c. It is performed by multiplication.

Reduction Ascending is changing numbers of a lower denomination to a higher denomination; as farthings to pence, &c. It is the reverse of Reduction Descending, and is performed by division.

ENGLISH MONEY.

127. English or Sterling Money is the currency of England.