last digit

how to know the last digit of a 1000 digit long number …
also can we also store such a large number in c++…
if yes, how…

first calculate the length of the number, and den use the “percentile” method of calculating the last digit.

fo example:

no= 46484881454

here, no of digits= 11

so
lastdigit= no%pow(10,11)
where 10 is constant and 11 is the no of digits in the given number.
pow is the function in mths.h library file…

hope you lyk the answer.
thanks

1 Like

and we can store large digits in c…

use ‘double’, ‘long int’, etc etcc…

Hello,

It depends on how this 1000 digit number is given to you…

If it is given in input, you can read it as a string and you are done :slight_smile:

If it is the result of a series of calculations that get more and more complex and possibly lead to overflow, then the best way is to use an array to hold the digits and perform grade-school arithmetics like you were taught when you were young :slight_smile:

It will also obviously depend on the kind of operations being performed, but, for multiplications, you can read a post I made to solve the problem Small Factorials.

There, I briefly explain how to handle very large numbers using an array, you can find it here and I hope you find it helpful!

Best regards,

Bruno

4 Likes

u mean 2 say i shud store it in a string and then calculate its length … and then proceed.

hi @callam2pm well i dont think you can store this big number as a “number” in c++.

The obvious solution is to use String. String is a sequence of characters. Unlike ints and longs which have a paticular predefined range, strings dont have any such restriction(Except for the memory limit itself!).

So, here is the c++ code you might be looking for.

#include<iostream>
#include<cstring>
using namespace std;
int main()
{
   char num[1001];
   cin>>num;

   // if the number is exactly of 1000 digits always then to get the last digit simply:
  // cout<<"the last digit is:"<<num[999];

 // if the number isnt of 1000 digits exactly then u must find its length first:

 int length = strlen(num); //this function returns the length of the string
 cout<<"the last digit is: "<<num[length-1];
 return 0;
}

Hope this helps :slight_smile:

1 Like

As I said…It depends on how the number is given to you, read my answer above

u can also store it in strng format. bt dere will be a prblm. u cant use mathematical operations on string format.
so its better to use long int , double… etc etc

long int, double and etc etc as you say, can never, ever store a number which is 1000 digits long…So a string should be used… Plus, if only the last digit is needed, such operation can be done easily on a string.

1 Like

@sailesharya no you cannot use these inbuilt datatypes they can not store such a long number.
Go to this page and scroll down a bit you will see a table having range of various variables like char int, long etc. that will make thing clear for you :slight_smile:

1 Like
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