Iowa territorial gazette and advertiser. [volume] (Burlington, Iowa Territory [Iowa]) 1840-1846, 1843-12-02
Interest.

a Dialogue betVes. Teacher aad his Pupil.
Teacher.--What 10 the common rule for &C
curing interest?
PoPlf..Multiply the principal by half the
number Of months.
eT;s-Why doyou multiply BY half the number
P.-Because the principal shows the interest
for two months: that is, the interest for any
sum for two months, or sixty days, is as many
cents, as dollars in the principal; to wit. SIS
two months is Is cents interest, 5000 cents,
&C.; therefore, it is evident If the interest is given
for two months in the principal, it must be null
tiplied by half the given number Of months to
give the true interest.
T.-How do you proceed, when the interest
is required for odd months, 5, Z, or 3?
P.-For months, multiply BY 2 l-2, for I,
s l-2 sc.
T--When there are days given, how do you
proceed?
P.-I multiply BY one-sixth part of the lays,
or take aliquoit parts ofthe principal
T-Why do you multiply by one-sxth part
of the days?
P.--Because the sixth part Of the days, is a
decimal fraction Of 60 days; that is, the sixth Of
II days is 2; which means 2-lOths of 60.
T.--When months and days are given, where
do you place the sixth of the days as multi
plier?
PAT the right hard Of the given number Of
months and point it Off as decimal.
T.--What rule have you fer pointing off the
product, SO as to show the answer in dollars,
Nc2
| PAS the principal in dollars expresses the
Interest in cents for two months, the product, al
ter multiplying by half the number of months,
will be cents. | reduce the cents to dollars, BY
pointing IS s-~A 6s.a.>a frnra Aha right. urhiAh
are cents; those on the left are dollars IT mere
Are cents and mills in the principal, they are de-
cimals. I therefore cut off as many figures from
the right (which are mills and parts of mills) and
reduce those on the left as before. If multiply
Nv cne.sixth of the days, cut off one more fig.
TIRE from the rght-the sixth Of the days being Z
\ decimal.
T.-Wheh you take the aliquoit part Of tn
principal, what do you consider the principalp
P.-The interest in cents for 60 days.
T-Iso you always take the aliquoit part q
the principal as the interest fot 60 days2
P.-I do not. II the days are less than six,
consider the principal Of mills, showing the in
terest for six dayss that Is, the interest Of an!
sum for six days is A. many mills Is dollars II
the principal.
T.-How do you explain this? =.
P.-As the principal expresses the interest il
tents for sixty days. and as six days is one-tent
IF sixty, and One mill one-tenth Of a cent: 1t
evident that the principal expresses the interes
in mills for six days, on the same principal the
1t does cents for sixty days.
T--Ho~ do you GENERALLY cast INTEREST,"
Ply analysis. =
T.-What Is the interest Tor $40, FIR tw
months and three days?
P-The interest Of $40, for two months, Is :
many cents as dollars; that 10, 40 cents3 Il
three days, half Is many mills, {: .. 30--equal
two cents; therefore, the interest is AZ cents
T.-What is the interest. for $50, for hv
months and nine days?
P.-The interest Of $50 for two months, is {
cents; for 4 months, twice SOTO $50 cents; Il
one month, half of 500 CENTS; 20 added TO- Y
equals 200 cents, the interest for month: In
interest of $50, six days il 80 mills; for thr:
days are half Of $40 mills, 30 mills and
mills make 100 mills-equal to II cents; Y cen
added to 200 cents, make 2l2 cents Or $2,i2, h
answer.