How to write python program to calculate simple interest


In this article we will learn How to write python program to calculate simple interest in step by step. Let’s see:

Follow simple steps to write python program to calculate simple interest

Step 1 – Note down the formula of simple interest.
SI=(P×T×R)/100
Here, SI is simple interest
P is principal amount given for interest
T is time period for which P was given for interest
R is the rate of interest

Step 2 – Identify the variables in the formula.
We can clearly identify that P, T, R are the required variable.

Step 3 – Decide how the variables are going to get their values.
I am planning to give the variables their values by asking the user for input.

Step 4 – Decide how we will implement the above formula, namely through a class or a function or through simple sequential input, calculation of answer, and output.
I am going to define a function to calculate and return the value of the Simple interest calculated from the inputs given by user.

Step 5 – Decide the IDE we are going to use for programming.
I am going to use Spyder IDE which comes in the Anaconda distribution.

Step 6 –Declare the function, I am using SI as the function name.

How to write python program to calculate simple interest.

Decide the IDE we are going to use for programming
Decide the IDE we are going to use for programming

Step 7 – Write statements to ask user for the values of P, T, R when the function is called.

step 2 python program to calculate simple interest
step 2 python program to calculate simple interest

Step 8 – Writing an “if name == ‘main’” block to call the function SI() in order to test it. “if name == ‘main‘” block runs the code in it only when the program is run directly and not imported.

step 3 python program to calculate simple interest
step 3 python program to calculate simple interest

Output:

output python program to calculate simple interest
output python program to calculate simple interest


Step 9 – We need to make sure that only numbers are inputted while asking for input.
To do that, I am going to put each input statement in its own while loop. The while loop will be exited when a number is inputted. Checking if the value inputted is correct is done by checking if it can be converted into a floating-point number. Since converting a string containing characters other than numbers into floating-point numbers results in a traceback, I am using try and except block to achieve this part.
In the try block I am trying to convert input into floating point value. If an error occurs then the flow jumps to except block where I am just going to ask the loop to continue. This goes on until a valid input is given.

Step 9 python program to calculate simple interest
Step 9 python program to calculate simple interest

Output :

 python program to calculate simple interest
python program to calculate simple interest

Step 10 – We can further refine the code by printing the user to print valid inputs when he enters invalid inputs and telling the units in which we are taking inputs.

Step 10 python program to calculate simple interest
Step 10 python program to calculate simple interest

Output:

Step 10 python program to calculate simple interest
python program to calculate simple interest

Summary :

In this article we saw How to write python program to calculate simple interest so about this article you have any query then free to ask me

I am Mr. Sachin pagar the founder of Pythonslearning, a Passionate Educational Blogger and Author, who love to share the informative content on educational resources.

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