Changing CommonLit Percentage Scores to Fractions Cheat Sheet

CommonLit percentage scores can be converted into fractions by treating the number of questions answered correctly as the numerator and the total number of questions answered as the denominator.

If there are Part A/Part B questions, this may affect the denominator, as CommonLit discounts Part B questions from the total score when a student gets the corresponding Part A questions wrong.

For example, say a quiz has 5 questions:

1. Part A Multiple Choice
2. Part B Multiple Choice
3. Part A Multiple Choice
4. Part B Multiple Choice
5. Short Answer

If a student gets question 1 (Part A) incorrect, then we discount question 2 (Part B) from the total score. As a fraction, this means the denominator changes from 5 to 4. Since a student already got one question wrong, at most, she can get a 3/4 now.

If there are 10 questions and the student gets 2 part A questions wrong, we remove their corresponding 2 part B answers from the score, making the denominator 8 instead of 10. Since the student already got 2 questions wrong, at most, he can get a 6/8 now.

What if your gradebook options are limited and you cannot change the denominator? What if an assignment can only be worth a certain amount of points for all students? Then you can use some fraction conversion formulas to calculate a new numerator without changing the denominator.

If a student got 3/4 on a quiz with 5 original questions, this is how you find the new numerator:

3/4 = x/5

3/4 * 5 = x

.75 * 5 = x

3.75 = x

To check out math, 3.75/5 = .75 = 3/4.

Here's a quick cheat sheet on some of the most common combinations you'll see on CommonLit assignments. When you see the denominator go down, it means the student got 1 or more part a answers incorrect and lost 1 or more part b answers from their denominator.

Keep in mind that short answer questions can throw off these round numbers. For the examples below, we're assuming the students got a full score for their short answer question.

4 total questions:

1 Part A/B Question Set

2/3 = 2.67/4

1/3 = 1.33/4

5 total questions:

1 Part A/B Question Set

3/4 = 3.75/5

2/4 = 2.5/5

1/4 = 1.25/5

2 Part A/B Questions Sets

1/3 = 1.67/5

10 total questions:

1 Part A/B Questions Set

8/9 = 8.89/10

7/9 = 8.78/10

6/9 = 6.67/10

5/9 = 5.56/10

4/9 = 4.44/10

3/9 = 3.33/10

2/9 = 2.22/10

1/9 = 1.11/10

2 Part A/B Questions Sets

7/8 = 8.75/10

6/8 = 7.5/10

5/8 = 6.25/10

4/8 = 5/10

3/8 = 3.75/10

2/8 = 2.5/10

1/8 = 1.25/10

3 Part A/B Question Sets

6/7 = 8.57/10

5/7 = 7.14/10

4/7 = 5.71/10

3/7 = 4.29/10

2/7 = 2.86/10

1/7 = 1.42/10

4 Part A/B Question Sets

5/6 = 8.33/10

4/6 = 6.67/10

3/6 = 5/10

2/6 = 3.33/10

1/6 = 1.67/10

5 Part A/B Question Sets

4/5 = 8/10

3/5 = 6/10

2/5 = 4/10

1/5 = 2/10

Click here for guidance on the math.