MATHS SIMPLE INTEREST AND COMPOUND INTEREST SHORTCUT TRICKS

SIMPLE INTEREST 

we have using these BASIC formulas

S.I. = PxRxT / 100

BUT there are some example how these shortcut tricks that

Type 1.

In how many years will a sum of money double itself at 12% per annum?
a. 6years 6 months
b. 7 years 6 months
c. 8 years 3 months
d. 8 years 4 months

Type 2.
 at what rate of percent of simple interest will a sum of money double itself in 12 years?
a. 8%
b. 8.1/3%
c. 8.1/2%
d. 9.1/2%

Type 3.

The rate at which a sum become four times of itself in 15 years at simple interest will be?
a.15%
b. 17.1/2%
c. 20%
d. 25%

Type 4.

if a sum of money at simple interest double in 6 years. it will become 4 time in ?
a. 12 years
b. 14 years
c. 16 years
d. 18 years

Type 5.

How long will it take a sum of money invested at 5% p.a. by simple interest to increase it value by 40%?
a. 5 years
b. 6 years.
c. 7 years
d. 8 years

COMPOUND INTEREST SHORTCUT TRICKS

Type 1.
a sum of money place at compound interest double itself in 5 years. It will become 8 times itself at same rate of interest in ?
a. 7 years
b. 10 years
c. 15 years
d. 20 years

Type2.

By C.I. at 10 % p.a. a sum increased to 2662 in 3 years what will be the principal amount ?
a. 1000
b. 1500
c. 2000
d. 2500

Type 3.

In C.I, what will be the rate of interest if a sum becomes 1331 in 3 years?
a. 100

b.1000
c.10000
d. none of these

Source : http://www.questionpaper4exam.com/2015/06/maths-simple-interest-compound-interest-shortcut-tricks.html