SHORT CALCULATION. 763 



to call the number of yards the price, and the price the number of yards, 

 in order to make the computation, as in the example above ; 50 yards @ 

 Si. 18 would be the same as 118 yards @ 50c. ; or to say, if 100 yards @ 

 81.18 would be $118, 50 yards would be half of that amount, or $59. In 

 the first example we say, if 35 yards @ $10 per yard would be $350, at 

 '0 per yard, it would be one-fourth of that amount, or $87.50. 



INTEREST. 



861. To find the interest on any amount, at any rate per cent, for any 

 length of time : 



First. Reduce time to run on interest to months and tenths of a month. 

 To find the number of tenths of a month, divide the number of days over 

 a month by three, then add to the number of months the tenths, in decimal 

 form. 



Second. Move the decimal point between dollars and cents in the prin- 

 cipal two places to the left, divide this amount by twelve, and multiply by 

 the rate per cent. ; multiply this amount by the number of months, as found 

 above, and the product will be the answer. 



EXAMPLE. $360. 00 7 V cent, for 2 years, 5 months and 18 days. 

 SOLUTION. 2 years, 5 months and 18 days equals 29.6 months. 

 12)3.60 (Move decimal point two places to the left.) 



.30 (Divide by 12), 

 .7 (Multiply by the rate per cent.) 



2.10=Interest on principal for one month. 



If $2.10 for one month, for 29.6 month* it would be 29.6 times $2.10 or $C'J 

 Answer. 



AT TEN PER CENT. 



First. Find the number of months and tenths of a month as in j.r 

 ing item. 



Second. Move decimal point between dollars and cents in principal <>/</' 

 'ft, divi.lr \ytwelve, then multiply this amount 1'Vthc num- 

 ber of months, as f<mn 1 In M finV' *nd the product will be the ana* 



MPLS. $600.00 10? cent., from August 7 .lanuary 



August 7, 1S77, t. .J.umary 28, l.v 

 'Jl (l.iys, which r.ju.-ils 17.7 months. 



12)60.00 (Move decimal point one placv t.. tho left.) 



6 (Divide by twtl ve.) Which t<[ii;i!s intnvst <>n tin- i>rinnp:il for one 

 month. 



