Exercise and Solution

var number = prompt("What is your number?");
number = parseInt(number);
var grade;

if ( number <= 100 && number >= 80 ) {
    grade = "A+";
} else if ( number < 80 && number >= 70 ) {
    grade = "A";
} else if ( number < 70 && number >= 60 ) {
    grade = "A-";
} else if ( number < 60 && number >= 50 ) {
    grade = "B";
} else if ( number < 50 && number >= 40 ) {
    grade = "C";
} else if ( number < 40 && number >= 33 ) {
    grade = "D";
} else if ( number < 30 && number >= 0 ) {
    grade = "F";
} else {
    grade = "Invalid Input!";
}

console.log("Your Grade: " + grade);

console.log("Select an Option: n1. Add n2. Subtractn3. Mulitply n4. Divide");

var num1 = prompt("Enter First Number: ");
var num2 = prompt("Enter Second Number: ");
var option = prompt("Choose an operation: ");
var result = null;

num1 = parseInt(num1);
num2 = parseInt(num2);
option = parseInt(option);

var num1Con = isNaN(num1);
var num2Con = isNaN(num2);
var optionCon = isNaN(option);

if (num1Con || num2Con || optionCon) {
    console.log("Invalid Input!");
} else {
    switch (option) {
        case 1:
            result = num1 + num2;
            break;
        case 2:
            result = num1 - num2;
            break;
        case 3:
            result = num1 * num2;
            break;
        case 4:
            result = num1 / num2;
            break;
        default:
            break;
    }

    if (result == null) {
        console.log("No Result!");
    }
    else {
        console.log("Result: " + result);
    }
}