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We're starting with the very important concept that is a Biton functions how to write functions in our

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python programming.

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Whenever we write the long code, then also we try to divide that code, segregate that code into multiple

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different models and functions.

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And whenever functions are there, then it will make us easier to understand that program.

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And obviously the reusability of the code can be enhanced by writing one related one function containing

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related statements which are executed as a whole whenever such an operation will be asked for.

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So let us go for the further discussion on this function of in Python.

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So function is a group of predicate statements that perform a specific task in our program function

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implementation breaks up a program into smaller and modular chunks and function helps us to make our

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program more modular, organized, easy to debug, reusability will be enhanced and so on.

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It is really features helps us to avoid repetition of our programming code, syntax of a passive function,

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how to write one function in our python so def will be written.

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That is a different function, so defined function also we can define so def will be there.

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So this is a function name.

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These are the list of parameters you may or may not pass, obviously, so list of parameters added.

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Don't forget to give the school on because if you get this call, that means you are starting with the

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function body and the function body will have that indent in that case.

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And there is a string which has been enclosed within three skorts the double there.

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So there is a GOC string doxxing if you want to insert the doctrine that is that documentation string,

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that should be the first statement within the function body.

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And then we can write one or more than one statement and then return value return and then return value

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would be there.

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And that is optional.

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A function may or may not return a value.

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So there is a way to write the function in about Biton.

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Types of functions, basically functions can be divided into the following two types, the first one

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is the building functions, the functions that are built into the python as an example, ebb's, which

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will give you the absolute value of the input parameter and then character with having to see each other.

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So there is a flow, there is a conversion to the float.

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That is, the print will be using this print, whether using this print multiple times in our python

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code to print some string on the screen, on the console.

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So these are the inbuilt functions.

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There is a built in functions we need not to write that is code for all these functions there.

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But I can readily use them in our code as when required.

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So next one is our use, the different functions and these functions.

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We are responsible to write the body and the function defined by the users themselves and to do certain

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specific tasks.

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All of us remember the function name should be very much, very much important because it is a different

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function from the function name.

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Who should get the purpose of the function.

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If you give the function name like function one function to function three, they don't carry an instance

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in future.

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So next time, if you if I ask you what is the purpose of function, one, you are supposed to look

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at the code, but the function name should be pretty much logical, very much meaningful, so that from

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the function name event you can get the purpose of the function.

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I let us go for one practical demonstration to show you how to write these functions in our Python programming

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with some simple coding.

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So here is the demonstration in.

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We are going to discuss functions and in case of Python functions, the function names should be defined

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and here will be using the keyword.

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There is a defined that is a diff and the function name within the opening and closing prospect.

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We can write the respective parameters if I want to pass some input parameters there.

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This is known as it was a different function because we are writing their respective function, but

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also function should be should have this opening and closing bracket that will indicate that it is a

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function here as here we are writing the function body.

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So it will be known as the user defined function.

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But if you don't write the function body, that means in case of print, you can easily find that this

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print is a function because it is having this opening our first record and the closing possibilities

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and it is taking a string as input parameter.

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But we are not writing the body of the screen.

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So that is why it is called library function or inbuilt function.

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After writing this def and then function, then opening back at closing bracket, then we shall put

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one colon here.

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Then this is part of the function body will have the indentation, which is the four blank spaces are

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there.

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So all the statements which will be maintaining this for blank spaces beforehand will be treated as

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a part of the function body.

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OK, so in this way that is no big and there is no culebras open.

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Culebras close, there is no block begin and block end marker.

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Only this indentation will indicate that these statements are within this function bodies.

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So this is this one is a function which is having no return statement.

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You can find that there is no written statement we have written, but in return we are having one return

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statement and it is having this string to be returned, return common returns, back the control to

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the column, and mainly used to return a value to the column of the function.

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So whenever we are calling this one, then this print statement will get executed because this is the

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only one statement within this one function body.

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But in case of Halo two, when we'll be calling this, it will return one string so the content will

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come back to the caller when this return statement will be executed and then print will print that this

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particular print function of print method will print the string, which will be returned here.

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So let us go for the execution.

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You can find this is the outcome of hello one hello, one function calling.

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And this outcome of this print has to function so a function can have the first step in which will be

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in the indentation will be known as the document string or string if it is enclosed within our triple

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single course or triple double code.

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So I can write this one as and this one.

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So this is.

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This is a.

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Multi-line text, so I've written this one within tripple single quotes.

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Now this is known as the dark string, and this docketing is a first step in this function body, which

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is having that in the indentation.

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OK, so how to access this one so we can do this one in this way?

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So in this way, I can access this tape and string or documentary, it can easily find this is in my

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line text instead of enclosing it within a single triple single cause, I also can use them as double

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quotes.

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Then also, it will have the same output as I've you.

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OK, next, we are going for the other program part here.

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One thing has to be remembered here.

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This one is that it was a different function because we are writing the function body.

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This Halbertal is that it was a different function because we are writing this function body.

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But this print is a function or the library function because we're not writing the function body of

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print, but we're using it, we're calling it according to our purpose.

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So that's why this print is known as the library function here.

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Here to define multiple functions, so first function is my addition, which takes X and Y as input

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document.

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So here the key word def there is a defined function name and then input arguments included within opening

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and closing must be there.

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And it is the body of the function which is printing this statement that is performing the addition,

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Operation and Return X, plus similarly written the function body for subtraction, performing the subtraction

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operation return X minus Y, my multiplication which is taking X and Y as input parameters, performing

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the multiplication operation Return X started while my division it is taking this X and Y as input arguments.

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So print performing that division, Operation Return X by white.

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So in this way we have defined my additions, my subtraction, my multiplication, my division methods

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now are going to define another method that is known as my menu.

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All these methods that user defined, user defined functions.

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So under this my menu are having this amendment will be printed.

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Therefore options are going to get printed.

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Then it blocks for the for the option number.

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Then it will accept the option number he had.

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Input is a function library function which returns a string.

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So before assigning it to the variable, I'm doing the typecasting using another inbuilt function library

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function.

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That is a..

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So now it will return the value of S.H. So my menu returns the value of S.H. Let us go for the final

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function that is about UNDEF calculation so that it is calling my menu.

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So my menu will print this, my menu and the four options and it will accept for the choice and then

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the value will be returned to value which will be returned, will be assigning, will be assigned to

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this.

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S.H. It does not mean that here the variable is C.H. So here also we are supposed to have the variables

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and you can also make it as choice.

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So that is not an issue because this choice is is local within this menu and this is local within this

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calculation.

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So they may be having the same name, maybe having the different name, but in both cases they will

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have their separate memories with allocation during execution of our code.

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So here we have we agreed to number one.

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And number two, it was in the same way.

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Please enter the first number.

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Please enter the second number, input function returns string.

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So it has been converted to integer using IMT here.

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So if the value will be returned by this, if it is equal to one, then the result is equal to you.

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See, I'm calling this my addition function.

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And number two, I'm passing two parameters.

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This number and number will get assigned onto X and Y.

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You can find it and then it to return the sum of it after printing this line.

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So that result will be assigned to this result so that some will be assigned to this result.

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Four tries to return the respective difference that will be assigned to result in case of choice three,

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the respective product will be returned and that will be assigned to the variable result in case of

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choice for the respective quotient will be returned and that will be assigned to the variable result

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here.

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So print result is able to result.

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So I'm going to print that one.

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So if I call this respective function, that is calculation.

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You're going to go for the calculation.

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You can find that it is at first it is calling this myman I.

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My menu is displaying the options and it is asking for the option number.

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If I give the option number one, then it is asking for the first number.

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Let it be one hundred and the second number, let it be two hundred.

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So as a result of that, as I selected option number one, so additions will be done between 100 and

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200.

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So as a result we are going to get 300 here if I execute the code once again.

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So here I'm going for the option number two, I'm going for the multiplication between 10 and 20 you

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can easily find.

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So I'm getting the I'm getting the subtraction.

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I've selected.

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Option number two.

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It is for the subtraction.

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So good getting here minus ten as the outcome.

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So let me show it once again.

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So here I'm going for option number two.

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That is a subtraction.

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So I'm just giving the value one hundred and giving the value forty.

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You can find that performing the subtraction operation.

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So because this particular line has got printed, because I wrote that one in our minds, a production

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method and then it is returning X Y and that will be assigned to the result and and later.

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So result is equal to the result.

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Variables value will get printed.

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So result is equal to sixty is getting printed because we have given inputs one hundred and forty.

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So the difference will be sixty here.

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So let us go for the third option.

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So option number three, so now it is multiplication.

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So if I give the value one hundred and twenty, so the result is coming as two thousand performing the

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multiplication of.

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So result is a goal to 2000 here.

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So let us go for the last one.

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So if I give the option number four, I'm supposed to perform the division operation.

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So the question will be returned.

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I'm giving this one hundred and twenty five.

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You can find that it is giving me the result.

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As for Bunjil, so in this way, you can easily find that we have written some code here for the better

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explanation and for your better understanding.

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So a function can return, a return value may not return a value.

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A function should should be starting with this difficult which is defined then the function name, then

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opening bracket.

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Closing bracket will include the input parameters, then colon is master and all the all the statements

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which will be written with, with intent.

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So they will be treated within the function body.

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You can find out how we are writing this code and how the function is getting called here.

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So I think the conception is getting clear to you that how this function can work.

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So I'm giving you one assignment.

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We know that division by zero is illegal.

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So that's why whenever you are performing this division operation before performing the division, obviously

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I should check the value of Y.

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If the value of Y is negligible, then obviously I should handle the situation carefully.

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So please modify this code and so that you can also check with the division by zero is illegal, is

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happening or not, and accordingly modified this code and write and write the program yourself.

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Thanks for watching this video.