British Exchange.
Adding Pounds, Shillings and Pence.
To add English money on the Comptometer, the pence are added first, and when the bottom of the column is reached, a few strokes on the keys divides it by 12 and places the number of shillings thus found in the next higher column of the register, so that adding the columns of shillings up it will be included in the shillings, while the remainder of the pence will stand to the right. Then after adding up the shillings column and dividing the sum thus obtained by 20, the pounds are added up and the entire sum total in pounds, shillings and pence is indicated on the register.
As each division is made the machine throws the quotient into the proper column, where it is included in the footing of the denomination to which it belongs. As compared to the mind, it saves even more time in adding pounds, shillings and pence than in adding ordinary numbers expressed by the decimal system.
RULE.—First add the pence on the two right hand columns of the machine and divide by 12. The quotient is shillings and the remainder pence. Leave this standing on the register; add up the shillings on the third and fourth columns of the machine. Divide the footing of the shillings by 20 (in doing which you do not touch the three right hand columns of keys). Then add the pounds on the fourth and higher columns of the machine, and the sum total in pounds, shillings and pence is indicated on the register: pence in the first and second columns of the register, shillings in the third and fourth columns of the register, and pounds in the fifth and higher columns of the register.
