50 Math Riddles for Middle School With Answers
Math riddles for middle school work best when students have to reason, not just calculate. This collection includes 50 riddles with answers for grades 6–8, covering number patterns, fractions, percentages, algebra, geometry and logic.
Use them as bell-ringers, brain breaks, team challenges or early-finisher activities. The first questions are quick; later ones require several steps.
Jump to: Numbers · Fractions · Algebra · Geometry · Logic
10 Number Riddles for Middle School
- I am greater than 30 and less than 40. I am divisible by both 3 and 4. What am I?
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36.
- I am the smallest positive number divisible by 4, 6 and 8. What am I?
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24.
- What comes next: 3, 6, 12, 24, 48, ___?
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96. Each term doubles.
- Three consecutive integers add to 72. What are they?
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23, 24 and 25.
- I am a two-digit number. My digits add to 9, and I am divisible by 9. What could I be?
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Any two-digit multiple of 9 whose digits sum to 9, such as 18, 27, 36, 45, 54, 63, 72, 81 or 90.
- What is the next perfect square after 81?
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100.
- I am a prime number between 20 and 30. My digits add to 5. What am I?
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23.
- Double a number and subtract 4 to get 18. What is the number?
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11.
- What is the greatest common factor of 18 and 24?
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6.
- What is the least common multiple of 5 and 12?
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60.
10 Fraction, Decimal and Percent Riddles
- I am 1/2 written as a decimal. What am I?
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0.5.
- What is 25% of 120?
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30.
- I am 0.2 written as a fraction in simplest form. What am I?
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1/5.
- A pizza has 12 equal slices and 5 are eaten. What fraction remains?
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7/12.
- What is 3/5 of 50?
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30.
- Which is larger: 0.7 or 2/3?
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0.7, because 2/3 is about 0.667.
- A price falls from $80 to $60. What percent decrease is that?
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25%.
- What decimal is equal to 3/8?
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0.375.
- If 40% of a number is 24, what is the number?
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60.
- What fraction of an hour is 15 minutes?
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1/4.
10 Algebra Riddles for Grades 6–8
- If x + 7 = 19, what is x?
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12.
- If 3x = 27, what is x?
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9.
- If 2x + 5 = 17, what is x?
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6.
- If 5x – 10 = 40, what is x?
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10.
- A number plus itself plus 8 equals 30. What is the number?
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11.
- Twice a number is 6 less than 30. What is the number?
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12.
- If y/4 = 6, what is y?
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24.
- If 4a + 2 = 22, what is a?
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5.
- A number decreased by 13 equals 9. What is the number?
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22.
- If 3(n + 2) = 21, what is n?
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5.
10 Geometry and Measurement Riddles
- A square has side length 8 cm. What is its area?
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64 square centimeters.
- A rectangle is 9 cm by 5 cm. What is its perimeter?
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28 cm.
- Two angles of a triangle are 45° and 65°. What is the third?
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70°.
- A circle has radius 5 cm. What is its diameter?
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10 cm.
- A cube has how many faces?
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6.
- A rectangular prism measures 4 × 3 × 5 units. What is its volume?
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60 cubic units.
- What angle is formed by perpendicular lines?
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A 90° right angle.
- A square has perimeter 44 cm. What is one side length?
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11 cm.
- A triangle has base 10 cm and height 6 cm. What is its area?
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30 square centimeters.
- A full turn is how many degrees?
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360°.
10 Math Logic Riddles
- A bat and ball cost $1.10 total. The bat costs $1 more than the ball. How much is the ball?
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5 cents.
- If five machines make five items in five minutes, how long would 100 machines take to make 100 items at the same rate?
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5 minutes.
- A farmer has 17 sheep. All but 9 leave. How many remain?
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9.
- There are 5 people and everyone shakes hands once with every other person. How many handshakes?
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10.
- You have 10 socks: 5 black and 5 white. In the dark, how many must you take to guarantee a matching pair?
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3.
- A clock strikes 6 times in 5 seconds. At the same pace, how long does it take to strike 12 times?
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11 seconds. Six strikes contain five intervals, so each interval is one second; twelve strikes contain eleven intervals.
- A snail climbs 3 feet each day and slips 2 feet each night. How many days to escape a 10-foot well?
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8 days. It reaches 8 feet after seven nights, then climbs from 8 to 11 on day eight and escapes before slipping.
- A number is multiplied by itself and gives 144. What positive number is it?
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12.
- You buy an item for $30 and sell it for $36. What percent profit did you make?
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20%.
- A class has twice as many students as a group of 14. How many students are in the class?
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28.
How Teachers Can Use These Math Riddles
- Warm-up: Use one riddle before a math lesson.
- Think-pair-share: Students solve individually, then compare methods.
- Error analysis: Ask students to explain why a tempting wrong answer is wrong.
- Team game: Award points for both the correct answer and a clear explanation.
For broader puzzles, visit our middle school riddles, math riddles with answers, riddles for teachers and riddle collection.
FAQs About Middle School Math Riddles
What math topics are covered?
The riddles cover number patterns, fractions, percentages, algebra, geometry, measurement and mathematical logic.
Are these suitable for grades 6–8?
Yes. The collection starts with accessible arithmetic and moves into algebraic and multi-step reasoning suitable for middle school practice.
Do the riddles include answers?
Yes. All 50 include answers, and multi-step problems include short explanations.
Conclusion
These 50 math riddles for middle school turn number sense, fractions, algebra, geometry and logic into short challenges students can solve and discuss.
