Grade 8 Math Test is a free online practice test with 15 questions on integers, exponents, scientific notation, square roots, linear equations, slope, pythagorean theorem, volume, systems of equations, percent, angles, functions, statistics and irrational numbers. The questions use integers, exponents, scientific notation, square roots, linear equations, slope, the Pythagorean theorem, volume, systems of equations and irrational numbers. The test scores itself, and it shows the correct answer and an explanation for every question you miss.
Take it in test mode to see your score and answers at the end, or in practice mode to check each answer straight away. A printable version and an answer key are included, and the test takes about 28 minutes.
This test needs JavaScript. The questions and the answer key are also listed further down the page.
Grade 8 Math Test
Name: ______________________ Date: ______________
What is −5 − (−9)?
Answer: ______________
What is 2³ × 2⁴ written as a single number?
Answer: ______________
0.0032 written in scientific notation is a × 10⁻³. What is a?
Answer: ______________
What is the square root of 169?
Answer: ______________
Solve for x: 3x + 5 = 2x + 12.
Answer: ______________
Solve for x: 4(x − 3) = 2x + 6.
Answer: ______________
What is the slope of the line through (2, 1) and (6, 9)?
Answer: ______________
A right triangle has legs of 8 and 15. What is the length of the hypotenuse?
Answer: ______________
A cylinder has radius 5 cm and height 4 cm. What is its volume in cm³? Use 3.14 for pi.
Answer: ______________
x + y = 12 and x − y = 2. What is x?
Answer: ______________
A price of $250 goes up by 20%. What is the new price in dollars?
Answer: ______________
Two parallel lines are cut by a transversal. One co-interior (same-side interior) angle is 65°. What is the other in degrees?
Answer: ______________
If f(x) = 3x − 4, what is f(5)?
Answer: ______________
What is the mean of 4, 9, 12, 15 and 10?
Answer: ______________
Which of these is an irrational number?
A. √16 B. √25 C. √7 D. √36
Answer key: Grade 8 Math Test
- 4
- 128
- 3.2
- 13
- 7
- 9
- 2
- 17
- 314
- 7
- 300
- 115
- 11
- 10
- √7
What this test covers
- Integers (1 question)
- Exponents (1 question)
- Scientific notation (1 question)
- Square roots (1 question)
- Linear equations (2 questions)
- Slope (1 question)
- Pythagorean theorem (1 question)
- Volume (1 question)
- Systems of equations (1 question)
- Percent (1 question)
- Angles (1 question)
- Functions (1 question)
- Statistics (1 question)
- Irrational numbers (1 question)
How the test works
Test mode and practice mode
In test mode you answer every question first and see your score, the time you took and the answers at the end. In practice mode you press Check after each answer to see right away whether it is correct, with the explanation.
How answers are scored
For questions with a number as the answer, you can type a whole number, a decimal such as 2.5, or a fraction such as 3/4. A dollar or pound sign is ignored, and a fraction and its decimal value count as the same answer. Multiple choice questions have one correct choice.
Printing the test and the answer key
Use Print the test for a paper copy with a space for each answer, and Print the answer key for the matching answers. Both print without the rest of the page.
Questions and answer key
The questions
- What is −5 − (−9)?
- What is 2³ × 2⁴ written as a single number?
- 0.0032 written in scientific notation is a × 10⁻³. What is a?
- What is the square root of 169?
- Solve for x: 3x + 5 = 2x + 12.
- Solve for x: 4(x − 3) = 2x + 6.
- What is the slope of the line through (2, 1) and (6, 9)?
- A right triangle has legs of 8 and 15. What is the length of the hypotenuse?
- A cylinder has radius 5 cm and height 4 cm. What is its volume in cm³? Use 3.14 for pi.
- x + y = 12 and x − y = 2. What is x?
- A price of $250 goes up by 20%. What is the new price in dollars?
- Two parallel lines are cut by a transversal. One co-interior (same-side interior) angle is 65°. What is the other in degrees?
- If f(x) = 3x − 4, what is f(5)?
- What is the mean of 4, 9, 12, 15 and 10?
- Which of these is an irrational number? (A. √16; B. √25; C. √7; D. √36)
Answers and explanations
| Question | Answer | Explanation |
|---|---|---|
| 1 | 4 | Subtracting a negative is the same as adding: −5 + 9 = 4. |
| 2 | 128 | Add the exponents: 2³ × 2⁴ = 2⁷ = 128. |
| 3 | 3.2 | Move the decimal point 3 places to the right to get 3.2, so 0.0032 = 3.2 × 10⁻³. |
| 4 | 13 | 13 × 13 = 169, so the square root is 13. |
| 5 | 7 | Subtract 2x from both sides to get x + 5 = 12, then subtract 5: x = 7. |
| 6 | 9 | Expand to get 4x − 12 = 2x + 6. Subtract 2x to get 2x − 12 = 6, add 12 to get 2x = 18, so x = 9. |
| 7 | 2 | Slope = change in y ÷ change in x = 8 ÷ 4 = 2. |
| 8 | 17 | 8² + 15² = 64 + 225 = 289, and the square root of 289 is 17. |
| 9 | 314 | Volume = π × r² × h = 3.14 × 25 × 4 = 314. |
| 10 | 7 | Add the equations to get 2x = 14, so x = 7. |
| 11 | 300 | 20% of 250 is 50, so the new price is 250 + 50 = 300. |
| 12 | 115 | Co-interior angles between parallel lines add up to 180°, so the other is 180 − 65 = 115. |
| 13 | 11 | Replace x with 5: 3 × 5 − 4 = 11. |
| 14 | 10 | The sum is 50 and there are 5 numbers, so the mean is 10. |
| 15 | √7 | 16, 25 and 36 are perfect squares, so their roots are whole numbers. 7 is not a perfect square, so √7 is irrational. |
Tips for Grade 8 math
- Solve equations by doing the same thing to both sides, and collect the x terms on one side first.
- For slope, subtract the y values and the x values in the same order.
- The Pythagorean theorem only works for right triangles: a squared plus b squared equals c squared.
Frequently asked questions
How many questions are on this test?
There are 15 questions. Most students need about 28 minutes, but there is no time limit.
Can I print this test?
Yes. Use the Print the test button for the questions and Print the answer key for the answers. The full question list and answer key are also on this page.
Does the test show the answers?
Yes. At the end you see the correct answer and an explanation for every question, and in practice mode you see them after each question.
Do I need an account?
No. There is no sign-up. Your best score is kept only in your own browser.
What should I do if I miss questions?
Look at the skills table on your result page, read the explanations for the questions you missed, and take the test again. If a step in your working looks wrong, the answer checker on this site can help you find the slip.