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uh hello guys welcome to this video so
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in this video I will show you a Python
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program which will allow you to
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calculate the sum of all digits present
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in a number so this program is really
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interesting it is asked inside
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interviews and competitive programming
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as well so it basically uh whenever let
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me just execute this program and tell
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you how it executes so inside my VS code
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let me just execute this so here it will
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ask you to enter a number so I just need
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to enter a number let's suppose I write
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145 so 145 what this program will do it
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will actually calculate the sum of each
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digit so 1 1 +
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4 +
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5 so the answer the output should be 10
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5 + 4 + 1 so which comes out to be 10 so
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if I execute this now you will see sum
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of digits is equal to 10 so very simple
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program we take each digit which is
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present and then we calculate the sum of
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it let me take another example if I say
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3 4 5 6 fourdigit number now what
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happens it calculates 3 + 4 + 5 + 6 so
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now it comes out to be 7 + 5 12 + 6 18
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so the output should be 18 so now you
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will see sum of digits is 18 so now let
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me show you the actual program right
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here so we actually ask using the input
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function enter a number then we declare
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a variable sum of digits is equal to
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zero and for this we are using while
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loop we are looping through all the
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actual number here so while the number
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is greater than
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zero so here what we are doing we are
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getting the last digit by using the
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percentage operator so let me paste this
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program and show this visual execution
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of this program so for this I will use
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this famous website which is
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pythonutor.com it's a very good website
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if you want to visualize programs step
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by
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step so this is the website here let me
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paste this program and try to execute
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visual execution step by step so here it
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will actually ask you to enter a
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digit so it is asking you to enter a
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number so let me write a number here 3 4
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5 6 and click on submit so as soon as
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you click submit the number is
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registered as you can see as a global
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variable now we come to the next step we
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declare a variable sum of digits and
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this variable is set to zero so this
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variable is registered here this is set
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to zero now we come to the while loop
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here you can see while number is greater
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than zero as you can see our number is 3
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4 5 6 it is greater than zero so this
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condition evaluates to true now we will
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come to this while loop the very first
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thing we are doing here we are
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extracting the last digit from this
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number so what is the last digit six as
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you can see the last digit is six we
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using this operator which is percentage
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operator so what it is doing it is
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dividing it by 10 and getting the
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remainder so what comes when you divide
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3 4 5 6 by
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10 it basically we get the last digit as
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a remainder
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so 10 divided by 3 4 5 6 you just
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calculate by itself just divide
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this 10 3 are
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30 we get
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45 and then 10 4 are
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40 5 6 and 10 5
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are 50 so we get the six as the
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remainder so exactly we are doing the
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last extracting the last digit so we are
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getting six here and now in the next
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step we are adding this digit what we
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got six right here we are adding it to
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this variable which is by default zero
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so now in the next step we add this
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to this
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variable now again we divide this number
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that we got here
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this number by 10 so this is not the
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this operator this is called as
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percentage this is used to get the
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remainder so now this is a uh division
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operator so now if you divide this by 10
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we get 3 4 5 so as you can see this
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digit have been
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removed so in the previous step we just
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want to remove
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this so that's why we divided this by 10
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as soon as we do this we remove the last
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digit now we need to
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get this five so what we do we repeat
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the process so 3 4 5 is greater than
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zero now again we divide this by 10 to
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get
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this five here the last digit so again
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we get the last digit in this variable
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as you can see previously it was six so
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now again we divide we get the remainder
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and it is stored inside
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digit you can see when you observe this
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it's a very simple program what we are
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doing we are getting the last digit
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every
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time and then we add this to the sum of
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digits so 6 + 5 it will be 11 so as you
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can see 6 + 5 11 again we divide this
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and we remove this five for removing
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this we divide this whole number by 10
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so now this now this time this becomes
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34 again we do the uh while loop again
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we compare 34 is greater than zero now
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once again we need to get this digit
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which is
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four
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we apply this
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percentage now this becomes four 4 + 11
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now it becomes
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15 again we divide this to remove this
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four now this this becomes three again
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we compare it three is greater than
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zero again we get the remainder which is
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three so digit now will be three so 3 +
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15 is comes out to be 18 so this will be
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your output 18 so if I say now this
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becomes 18 previous this was 15 15 + 3
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is now
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18 so after that now we will compare
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that if
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three we will divide this 3 by 10 so 3x
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10 now number becomes zero so now 0 is
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not greater than zero so now the while
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loop will break and now it will print
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out sum of
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digits in the next step is
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18 so very simple program guys you can
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see how simple it is inside the while
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loop first of all we are removing the
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last digit to get the last digit we are
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using the percentage sign then we are
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adding it to this sum of digits and then
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we are dividing it to remove the last
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digits by the division operator it's a
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very simple program it will be asked
7:53
inside interviews and competitive exams
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you can explain it like this and thank
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you very much for watching this video
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and also check out my website
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freeattools.com
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uh which contains thousands of tools