C program to enter student marks and find percentage and grade

Write a C program to enter marks of five subjects Physics, Chemistry, Biology, Mathematics and Computer, calculate percentage and grade according to given conditions:
If percentage >= 90% : Grade A
If percentage >= 80% : Grade B
If percentage >= 70% : Grade C
If percentage >= 60% : Grade D
If percentage >= 40% : Grade E
If percentage < 40% : Grade F

Input marks of five subjects: 95
95
97
98
90

Percentage = 95.00 
Grade A

Required knowledge

Basic C programming, If else, Basic Mathematics

Logic to calculate percentage and grade

Did you remember you primary mathematics classes. In primary classes you have learnt about percentage. Just to give a quick recap I am putting below the formula to calculate percentage.

After you got the formula for calculating percentage. Let us now move on to the step by step descriptive logic to find percentage and grade.

1. Read marks of five subjects in some variable say phy, chem, bio, math and comp.
2. Calculate the percentage using above formula. Which is per = ((phy + chem + bio + math + comp) / 500) * 100. By applying little maths you can easily cut down this complex formula to simple one. Which is per = (phy + chem + bio + math + comp) / 5.
3. On the basis of per find grade of the student.
4. Check if per >= 90, then print "Grade A".
5. Check all remaining conditions mentioned and grade the student.

Program to find percentage and grade

/**
 * C program to enter marks of five subjects and find percentage and grade
 */

#include <stdio.h>

int main()
{
    int phy, chem, bio, math, comp; //Five subjects
    float per; 

    /* Reads marks of five subjects from user */
    printf("Enter five subjects marks: ");
    scanf("%d%d%d%d%d", &phy, &chem, &bio, &math, &comp);


    /* Calculates percentage */
    per = (phy + chem + bio + math + comp) / 5.0;

    printf("Percentage = %.2f\n", per);


    /* Finds grade according to the percentage */
    if(per >= 90)
    {
        printf("Grade A");
    }
    else if(per >= 80)
    {
        printf("Grade B");
    }
    else if(per >= 70)
    {
        printf("Grade C");
    }
    else if(per >= 60)
    {
        printf("Grade D");
    }
    else if(per >= 40)
    {
        printf("Grade E");
    }
    else
    {
        printf("Grade F");
    }

    return 0;
}