## TYPE 1

**To calculate Rate of Simple Interest when Principal becomes A/B times of itself:**

__Trick:1__
Rate of SI =

## Example 1

At what rate of simple Interest per annum a sum of money becomes 3/2 times of itself in 5 years?

__Solution__**To calculate Rate of Simple Interest when Interest becomes A/B times of Principal:**

__Trick:2__## Example 2

At what rate of simple Interest a sum of money becomes 4/25 times of Principal. If number of years is equal to the rate of interest?

__Solution:__
Let time= X (years)

## TYPE 3

**When a sum of money becomes N1 times in T1 years and N2 times in T2 years**

__Trick 3__## Example 3

A sum of money becomes 7 times of itself in 20 years . In how many years it will become 13 times of itself?

__Solution:__## TYPE 4

**To calculate Time when Principal becomes N times of itself and rate of Simple Interest is given:**

__Trick 4__

## Example 4

In how many years a sum of money becomes 4 times of itself at 10% rate of simple interest?

__Solution__## TYPE 5

**To calculate Principal when sum of interest or difference of interest for two different years is given**

## Example 5

At 6 % rate of simple interest per annum the sum of interest for 3 years and 6 years is Rs.270. Calculate the sum?