C Program to grade calculation system

Description

Get a mark of a stuent and find its grade.
(Note:
96 to 100 - O Grade 
91 to 95 - A Grade
81 to 90-B Grade
71 to 80 - C Grade
61 to 70 - D Grade
50 to 60 - E Grade
Below 50 - F Grade)

Input:
75
Output:
C

Solution

#include<stdio.h>
int main()
{
	int mark;
	printf("Enter a number:");
	scanf("%d",&mark);
	if(mark>95&&mark<=100)
	{
		printf("O Grade");
	}
	else if(mark>90&&mark<=95)
	{
		printf("A grade");
	}
	else if(mark>80&&mark<91)
	{
		printf("B Grade");
	}
	else if(mark>70&&mark<81)
	{
		printf("C Grade");
	}
	else if(mark>60&&mark<71)
	{
		printf("D Grade");
	}
	else if(mark>49&&mark<61)
	{
		printf("E Grade");
	}
	else if(mark>=0&&mark<50)
	{
		printf("F Grade");
	}
	else
	{
		printf("Invalid Mark");
	}
	return 0;
}
	

Explanation

chained conditional check is used here to check the mark range. any one of the grade will be displayed.