# Given a number N in decimal base, find number of its digits in any base (base b)

Given A Number n in a base 10, find the number of digits in its base b representation.
Constraints : Whole

Examples :

Input : Number = 48
Base = 4
Output: 3
Explanation : (48)10 = (300)4

Input : Number = 1446
Base = 7
Output: 4
Explanation : (446)10 = (4134)7


## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

A simple approach: convert the decimal number into the given base r and then count number of digits.

An efficient approach : It resides on the relationship between the base of the number and number of digits of that number.
Typically : Let n be a positive integer. The base representation of has digits if , which is the case if or .The number of digits in the base b representation of n is therefore In above equation the base changing logarithmic property has been used. So we calculate the logarithm of the number in that base which we want to calculate the number of digits. And take its floor value and then add 1.

This idea can be further used to find the number of digits of a given number n of base b in base r. All have to be done is to convert the number in base 10 and then apply the above formula of finding digits. It would be easier to calculate log of any base when number is in base 10.

## C++

 // C++ program to Find Number of digits   // in base b.  #include  #include    using namespace std;     // function to print number of  // digits  void findNumberOfDigits(long n, int base)  {      // Calculating log using base      // changing property and then      // taking it floor and then       // adding 1.      int dig = (int)(floor( log(n) /                            log(base)) + 1);              // printing output      cout << "The Number of digits of "          << "Number " << n << " in base "          << base << " is " << dig;  }     // Driver method   int main()  {      // taking inputs      long n = 1446;      int base = 7;             // calling the method      findNumberOfDigits(n, base);      return 0;  }     // This code is contributed by Manish Shaw   // (manishshaw1)

## Java

 // Java program to Find Number  // of digits in base b.  class GFG {             // function to print number of digits      static void findNumberOfDigits(long n, int base)      {                     // Calculating log using base changing          // property and then taking it           // floor and then adding 1.          int dig = (int)(Math.floor(                          Math.log(n) / Math.log(base))                          + 1);                                 // printing output          System.out.println("The Number of digits of Number "                             + n + " in base " + base                               + " is " + dig);      }         // Driver method          public static void main(String[] args)      {          // taking inputs          long n = 1446;          int base = 7;                     // calling the method          findNumberOfDigits(n, base);      }  }

## Python3

 # Python3 program to Find Number of digits   # in base b.     import math     # function to print number of  # digits  def findNumberOfDigits(n, base):             # Calculating log using base      # changing property and then      # taking it floor and then       # adding 1.      dig = (math.floor(math.log(n) /                  math.log(base)) + 1)             # printing output      print ("The Number of digits of"       " Number {} in base {} is {}"             . format(n, base, dig))     # Driver method      # taking inputs  n = 1446 base = 7    # calling the method  findNumberOfDigits(n, base)     # This code is contributed by   # Manish Shaw (manishshaw1)

## C#

 // C# program to Find Number of digits   // in base b.  using System;     class GFG {             // function to print number of      // digits      static void findNumberOfDigits(long n,                                      int b)      {          // Calculating log using base          // changing property and then          // taking it floor and then           // adding 1.          int dig = (int)(Math.Floor(            Math.Log(n) / Math.Log(b)) + 1);                      // printing output          Console.Write("The Number of digits"            + " of Number " + n + " in base "                         + b + " is " + dig);      }         // Driver method       public static void Main()      {          // taking inputs          long n = 1446;          int b = 7;                     // calling the method          findNumberOfDigits(n, b);      }  }     // This code is contributed by Manish Shaw   // (manishshaw1)

## PHP

 

Output :

The Number of digits of Number 1446 in base 7 is 4


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