1884 Simple Interest Rates

From Houghtaling's Handbook of Useful Information ©1884

Simple Interest Bales.
FOUR FER CENT.—Multiply the principal by the number of days to run; separate the right hand figure from the product and divide by 9.
FIVE PER CENT.—Multiply by number of days and divide by 72,
SIX PER CENT.—Multiply by number of days; separate right hand figure, and divide Dy 6.
SEVEN AND THREE-TENTHS PER CENT.—Multiply by number of days, and double the amount so obtained. On $1(X> the interest is just two cents per day.
EIGHT PER CENT.—Multiply by number of days, and divide by 45.
NINE PER CENT.—Multiply by number of days; separate right hand figure, and divide by 4.
TEN PER CENT.—Multiply by number of days, and divide by 36.
TWELVE PER CENT.—Multiply by number of days; separate right hand figure, and divide by 3.