Important Trick for Simple interest and compound interest

#everydayquiz #importantTrick #SimpleInterest and compound interest

Simple and Compound Interest

[y-1/x-1 ]*time    

[6-⅓-1 ] *5

5*5/2  

12.5 years

[Log y/log x]*t

[log9/log 3]*3

[Log 3^2/log 3]*3

[2Log3/log3]*3

Log 3 log 3 cancel..

So 2*3=6 years

Now new topic

After getting ratio just look at options and find multiple of 23

Answer will be multiple of 23 and 24 so you can search with 24 for easy calculation..

C will only divisible

44 increase

20% 2 yr ci =20+20+4=44

for 3 yrs =10.25+5+5*10.25/100 = 15.25+0.5125=15.7625

so 0.7625 % = 244

so 100% = 244*100/0.7625 = 32K

12.5+12.5+12.5*12.5/100  = 26.5625%

Given 26.5625%= 510

so 25% = 480

Here you can apply direct trick also,,

For two years there is formula

r*2.r^2

2*10.10^2

20.100   after point there must be 2 zeros

So

 1.00

20.

21.00  

Now 1800*21/100=378

So b is ryt

And other trick is

5% for two year ci will be

5*2.5^2  

10.25   now if we multiply 3200*10.25/100 = 328   

10+¼   3200  320   320*¼  =8   328

Another trick

20:21

400:441

So difference 41 units is 328 so sum 400 units 32000

Si for one year=10%

C.i. 10*2.10^2=21  

Difference: 21-10=11

11%=132

100%=1200  

first yr = 10%

second yr =11%

so 11% = 132

SO 100%= 132*100/11 = 1200

10:11

100:121

For second year interest will be 21-11 units so that is 132

1 unit is 12 so 100 units 1200