A practical system of mental arithmetic; or, A new and infallible method of making calculations by the mere action of a thought. 1st Lond. ed., stereotyped

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Σελίδα 67 - But if that sum is ahove 30, the excess in months of 31 days, or the excess above 29 in a month of 30 days, shows the age or days since the last conjunction. The moon's age taken from 30 leaves the day of the next new moon. When the solar and lunar cycles begin together, the moon's age on the first of each month, or the monthly epacts, are called the numbers of the month, and are as follows; viz. For Jan. Feb. Mar. April. May. June. These 0.
Σελίδα 56 - If the time consists of years, multiply the principal by the rate per cent., and that product by the number of years. EXAMPLE 1. — Find the interest of $75 for 4 years at 6 per cent.
Σελίδα 29 - ... or, If the price be an aliquot part of a pound, divide the given num6« г by as many thereof as nrjjjg u.
Σελίδα 7 - Prove one of the following rules of mental arithmetic in such a way as to make it intelligible to a class of children. 1. To find the value of 144 things in shillings, multiply the price in farthings by 3. 2. To find the interest of any sum of money for any number of months at any rate per cent., count one penny for each £10 in the principal, then multiply by the number of months and by double the rate per cent.
Σελίδα 5 - PREFACE lF arts and sciences are to be valued in proportion to their utility and importance, a System of Mental Arithmetic will hold a very high place in the estimation of a commercial public. Arithmetic, as generally taught in schools, is complicated and too tedious ever to be introduced into the counting-house, or to be pursued by the man of business. Every class of this extensive portion of society has most frequently to calculate the value of goods at the moment, and perhaps...
Σελίδα 64 - March the new moon falls nearest to the 21st in common years, or nearest the 20th in leap-years ; then the Sunday next after the full, or 15th day of that new moon, will be Easter-day. If the 15th day falls on a Sunday, the next Sunday is Easter-day.
Σελίδα 56 - TARLE for finding the Interest of any sum of money for any number of months, weeks, or days, at any rate per cent.
Σελίδα 67 - To ßnd the Leap Year. Divide the given year by 4, if nothing remains, it is...
Σελίδα 23 - Take nine times as many shillings, and four times as many pence, as there are pence in the price per pound.
Σελίδα 26 - RULE. Three times the number of pence per bushel, will be the value per chaldron, in shillings, and so of quarts, per firkin, and gallons per barrel.

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