Tips And Tricks And Shortcuts For Simple Interest Problems

Tips, Tricks & Shortcuts To Solve Simple Interest in Aptitude

To know the latest Tips and tricks and shortcuts of Simple Interest problems, go through the page entirely.

Simple interest is the  interest calculated on the principal portion of a loan or the original  amount. Simple interest does not compound, meaning that lender will only gain interest on the principal amount , and a borrower will never have to pay interest on interest already accrued. Simple Interest =  \mathbf{\frac{P * R * T}{100}}  .

Easy Tips & Tricks, Shortcuts of Simple Interest are given below:

Tips and Tricks for Simple Interest

General Formula and Shortcuts for Simple Interest

  • Simple Interest= \mathbf{\frac{P * R * T}{100}} 
  • Simple interest is calculated by multiplying the interest rate and  principal and number of days.
  • Here, are quick and easy tips and tricks on Simple Interest problems learn easily tricks and tips on SI and efficiently in competitive exams and recruitment drive process.
  • There are mainly 2 types of questions asked in exams. However, these questions can be twisted to check the students' understanding level of the topic. 

Simple Interest Shortcut formulas.

  • If the interest on a sum of money is \frac{1}{x}of the principal, and the number of years is equal to the rate of interest then rate can be calculated using the formula: \mathbf{\sqrt{\frac{100}{x}}}
  • The rate of interest for t1 years is r1%,  t2 years is r1%,  t3 years is r3 %.  If a man gets interest of Rs x for (t1+ t2 + t3 = n)  years, then principal is given by:
    \mathbf{\frac{x*100}{r_{1}t_{1}}} + r2t2 + r3t3
  • If sum of money becomes x times in t years at simple interest, then the rate is calculated as R = \mathbf{\frac{100(x-1)}{t}} %
  • If a sum of money becomes x times in t years at simple rate of interest, then the time is calculated as t = \mathbf{\frac{100(x-1)}{R}}
  • If an amount P1 is lent out at simple interest of R1% p.a. and another amount of P2 at simple interest of R2% p.a, then the rate of interest of the whole sum is given by: R = \mathbf{\frac{P_{1}R_{1}+P_{2}R_{2}}{P_{1}+P_{2}}}


Type 1: To find Simple Interest

Question 1. Find the simple interest of Rs 1000 for 10 years at 6% p.a.?


A. Rs. 60

B. Rs. 6000

C. Rs. 600

D. Rs. 6

Solution:    We know that,

SI = p*r*t/100

SI = 1000*6*10/100

SI = 60000/100

SI = Rs. 600

Correct option: C

Type 2: Simple Interest problem – When Rate of Interest is different for Different Years

Question 1. If a sum of Rs.25000 is given as loan for a period of 4 years with the interest rates 2%, 4%, 5%, and 6% for the 1st, 2nd, 3rd, and 4th year respectively. What is the total amount that has to be paid at the end of 4 years?


A. Rs. 29250

B. Rs. 29520

C. Rs. 25920

D. Rs. 25290

Solution:    As this is a case of Simple Interest we add 2% + 4% + 5% and 6% = 17%.

Amount = Principal + Rate of Interest.

Principal is 100% of the amount. 


Amount = 100% + 17%.

Therefore Amount = 117%

Amount = (117*25000)/100


Correct option: A

Type 3: Simple Interest problems To find the (Rate of Interest, Time period, Principal)

Question 1. A sum of money becomes 5 times in 20 years. Calculate the rate of interest.


A. 20%

B. 13%

C. 15%

D. 25%

Solution:    We know that, If sum of money becomes x times in t years at simple interest, then the rate is calculated as

R = 100 (x-1)/t %

R = 100 (5-1)/20 

R = 100 (4)/20

R = 400/20

R = 20%

Correct option: A

Read Also – Formulas for Simple interest in Aptitude