Problem Statements:

1. Given numerical grades and credits(weightage) of n subjects find CPI of the student. The grades are as follows:
     10
     9
     8
     7
     6
     0: Fail
  Accept the credits for each subject from user and calculate the CPI of the student.

  e.g. Grades obtained by a student in subjects s1, s2, s3, s4, s5 are 9,10,8,7,9 respectively
       Credits for s1, s2, s3, s4, s5 are 7,6,5,8,8
    CPI = Total grades obtained by a student(weighted sum)/Total no of credits
        = ( 9 * 7 + 10 * 6 + 5 * 8 + 8 * 7 + 8 * 9 ) / ( 7 + 6 + 5 + 8 + 8 )

Sample run:
Enter the number of subjects: 5
Subject1:
Credits: 7
Grades:9

Subject2:
Credits:6
Grades:10

Subject3:
Credits:5
Grades:8

Subject4:
Credits:8
Grades:7

Subject5:
Credits:8
Grades:9

CPI = 8.55

2. Given a number n, find how many bits are required to represent the number in binary.
  Generalize it for any base b.
  Do not use logarithm function.
 
  e.g.  base = 2    n = 16    o/p = 5 bits.
        base = 3    n = 47    o/p = 4 bits

  Representation of numbers in binary:
      We usually use decimal no system where base is 10. i.e. here, weights assigned to each position in the number are powers of 10.
    e.g. 1549 = 1 * (10 raised to 3) + 5 * (10 raised to 2)+ 4*(10 raised to 1) + 9* (10 raised to 0)

    Similarly, we can use binary number system where base is 2 and instead of 0-9 digits, we use only 0 and 1.
     e.g. 25 in binary is represented as 11001
         25 = 1*(2 raised to 4) + 1*(2 raised to 3) + 0*(2 raised to 2) + 0*(2 raised to 1) + 1*(2 raised to 0)

    The same way we can use any base b, the digits used to represent the number in that number system will be from 0 to (b-1)