main.js

// calculator logic:

let num = 10;
let num2 = 0;

let operator = '/';

if (operator === '+'){
    console.log(num + num2);   
}
else if (operator === '-'){
    console.log(num - num2);

}
else if (operator === '*'){
    console.log(num * num2);
}
else if (operator === '/'){
    if(num2 !=0){
    console.log(num / num2)}
    else {
    console.log("num2 cannot be zero");
}
}
else {
    console.log("invalid operator");
    
}


// student mark analysis:


let mark =30; // set the student mark
let bonus = 4;  

mark += bonus; // adding mark by bonus using assignment operator


let grade; // set the grade using by mark

if (mark > 90){
    grade = "A"
}
else if(mark > 70){
    grade = "B"
}
else if(mark > 50){
    grade = "C"
}
else{
    grade = "F"
}

// get the  mark result of student ,pass or fail using terenory operator

result = mark >= 50 ? "pass" : "fail";


// set the remarks using switch statement

switch (grade){
    case "A":
        remarks = "excellent"
        break;
    case "B":
        remarks = "good"
        break;
    case "C":
        remarks = "average"
    default:
        remarks = "needs improvement"

}

console.log(mark,result,grade,remarks)