Frequently Asked Questions
The formulas and conventions behind the factoring, slope, GPA and grade calculators, in plain words.
Factoring
What is prime factorization?
Writing a number as a product of primes, e.g. 360 = 2³ × 3² × 5. Every whole number greater than 1 has exactly one prime factorization (the fundamental theorem of arithmetic).
Is 1 a prime number?
No. A prime needs exactly two distinct factors, 1 and itself; 1 only has one. That's also why 1 gets no prime factorization of its own.
How do you factor a quadratic with the ac method?
For ax² + bx + c, multiply a·c, find two numbers that multiply to a·c and add to b, use them to split the middle term, then factor by grouping. The factoring calculator shows each of those steps for your numbers.
What if a quadratic doesn't factor?
If the discriminant b² − 4ac isn't a perfect square, there's no integer factorization. The roots still exist, and the calculator gives them exactly via the quadratic formula (as a simplified radical) and as decimals.
Slope
What is the slope formula?
m = (y₂ − y₁) / (x₂ − x₁), the rise (change in y) divided by the run (change in x) between two points.
When is slope undefined?
When both points share the same x-value, the run is 0 and dividing by zero is undefined. That's a vertical line, written x = k instead of y = mx + b. A slope of 0 is different: that's a horizontal line.
GPA
How is GPA calculated?
Each letter grade converts to points on the 4.0 scale, each course's points are multiplied by its credits, and GPA = total grade points ÷ total credits.
| Grade | A | A− | B+ | B | B− | C+ | C | C− | D+ | D | D− | F |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Points | 4.0 | 3.7 | 3.3 | 3.0 | 2.7 | 2.3 | 2.0 | 1.7 | 1.3 | 1.0 | 0.7 | 0.0 |
What's the difference between weighted and unweighted GPA?
Unweighted GPA treats every class the same (max 4.0). Weighted GPA adds a bonus for harder classes, commonly +0.5 for honors and +1.0 for AP/IB, so it can pass 4.0. The GPA calculator shows both. Individual schools sometimes use their own tables; check yours for anything official.
Grades
How does a weighted grade work?
Each category (homework, quizzes, tests) counts a set percentage of your grade. Multiply each category's grade by its weight, add them up, and divide by the total weight: that's your overall grade.
What grade do I need on my final?
needed = (target − current × (1 − weight)) ÷ weight, with the final's weight as a decimal. The grade calculator does this for you and tells you honestly when the target is already safe, or out of reach.