My solution

/* 
        Here's a little quiz.
        Answer correctly and "win" a prize.
        */
            alert("The following will be a short quiz for you. You can win a special prize for answering correctly. Good luck and here goes.");

        // quiz begins with zero correct answers
            var numberQuestions = 4;
            var answer = 0;

        // question 1
            var question1 = prompt("What is Kim Kardashian's husband's name?");
            if (question1.toUpperCase() === 'KANYE WEST') {
                alert("Congrats, you got that right. There are " + numberQuestions + " questions left.");
                answer += 1;
            } else {
                alert("Sorry, that was wrong. Keep trying. There are " + numberQuestions + "  questions left.");
            }
            numberQuestions--;

        // question 2
            var question2 = prompt("What is Earth's name in Latin?");
            if (question2.toUpperCase() === 'TERRA') {
                alert("Congrats, you got that right. There are " + numberQuestions + " questions left.");
                answer += 1;
            } else {
                alert("Sorry, that was wrong. Keep trying. There are " + numberQuestions + " questions left.");
            }
            numberQuestions--;

        // question 3
            var question3 = prompt("Which is the best city on this planet?");
            if (question3.toUpperCase() === 'NEW YORK' || question3.toUpperCase() === 'NEW YORK CITY' || question3.toUpperCase() === 'NYC') {
                alert("Congrats, you got that right. There are " + numberQuestions + " questions left.");
                answer += 1;  
            } else {
                alert("Sorry, that was wrong. Keep trying. There are " + numberQuestions + " questions left.");
            }
            numberQuestions--;

        // question 4
            var question4 = prompt("How many suns are there in our solar system?");
            if (parseInt(question4) === 1 || question4.toUpperCase() === "ONE") {
                alert("Congrats, you got that right. There is " + numberQuestions + " question left. You can do it!");
                answer += 1;
            } else {
                alert("Sorry, that was wrong. Keep trying. There is " + numberQuestions + " question left. You can do it!");
            }
            numberQuestions--;

        // question 5
            var question5 = prompt("How many legs does a spider have?");
            if (parseInt(question5) === 8 || question5.toUpperCase() === 'EIGHT') {
                alert("Congrats, you got that right. There are no more questions.");
                answer += 1;
            } else {
                alert("Sorry, that was wrong. There are no more questions.");
            }

        // output result
            if (answer === 5) {
                alert("Here is your score: Congratulations, you got all questions right!"); 
                document.write("Here's the GOLD CROWN for you!");
            } else if (answer === 4) {
                alert("Here is your score: Congrats, you got 4 out of 5 questions right!");
                document.write("Here's the SILVER CROWN for you!");
            } else if (answer === 3) {
                alert("Here is your score: Congrats, you got 3 out of 5 questions right!");
                document.write("Here's the SILVER CROWN for you!");
            } else if (answer === 2) {
                alert("Here is your score: Congrats, you got 2 out of 5 questions right!");
                document.write("Here's the BRONZE CROWN for you!");
            } else if (answer === 2) {
                alert("Here is your score: Congrats, you got 1 out of 5 questions right!");
                document.write("Here's the BRONZE CROWN for you!");
            } else {
                alert("Sorry, but you didn't get any answers right. No prize for you today.");
            }