These 70 math trivia questions for adults combine mental math, percentages, geometry, probability, number facts, and logic challenges. Each question comes with an answer and a short explanation, so you can use the rounds for a casual trivia night, a group game, or independent practice. Begin with the number-facts round, then move to the topics that suit your group.
Math trivia questions for adults: number facts and mental math
What is the smallest prime number?
Answer: 2. Explanation: A prime number has exactly two positive divisors: 1 and itself.
Which positive number has a square of 144?
Answer: 12. Explanation: 12 × 12 = 144.
What is 17 + 28?
Answer: 45. Explanation: Adding 20 to 17 gives 37; adding 8 gives 45.
Is 1 a prime number?
Answer: No. Explanation: It has only one positive divisor, not two.
What is 2 raised to the fifth power?
Answer: 32. Explanation: 2 × 2 × 2 × 2 × 2 = 32.
What is the greatest common divisor of 18 and 24?
Answer: 6. Explanation: Six is the largest positive integer that divides both numbers evenly.
What is the smallest positive multiple shared by 4 and 6?
Answer: 12. Explanation: The first positive multiple common to both is 12.
What is 99 × 6?
Answer: 594. Explanation: Calculate 100 × 6, then subtract 6.
Is 123 divisible by 3?
Answer: Yes. Explanation: Its digits add to 6, which is divisible by 3.
What is the remainder when 50 is divided by 7?
Answer: 1. Explanation: 50 = 7 × 7 + 1.
Fractions, percentages, and ratios in everyday life
What is 15% of 80?
Answer: 12. Explanation: 0.15 × 80 = 12.
A recipe for four people uses two cups of rice. How many cups are needed for six people at the same rate?
Answer: 3 cups. Explanation: Six people require 1.5 times the original recipe, so 2 × 1.5 = 3.
A $40 item is reduced by 25%. What is its price after the discount, before tax?
Answer: $30. Explanation: The $10 discount leaves $30.
A 60-mile trip takes 1.5 hours. What is the average speed?
Answer: 40 miles per hour. Explanation: Divide 60 miles by 1.5 hours.
A bottle contains three-quarters of a liter. How many milliliters is that?
Answer: 750 milliliters. Explanation: Three-quarters of 1,000 milliliters is 750.
A mixture uses one part concentrate to four parts water. How many cups of water accompany two cups of concentrate?
Answer: 8 cups. Explanation: The water amount is four times the concentrate amount.
A bill of $50 is split equally among four people. How much does each person pay?
Answer: $12.50. Explanation: $50 ÷ 4 = $12.50.
A price rises from $80 to $100. What is the percentage increase relative to the original price?
Answer: 25%. Explanation: The increase is $20, and 20 ÷ 80 = 0.25.
If two-thirds of 30 seats are occupied, how many seats are empty?
Answer: 10. Explanation: Twenty are occupied, leaving 30 − 20 = 10.
A 12-ounce bag costs $3. What is the cost per ounce?
Answer: $0.25. Explanation: $3 ÷ 12 = $0.25 per ounce.
Geometry and measurement trivia
What is the sum of the interior angles of a triangle in Euclidean geometry?
Answer: 180 degrees. Explanation: The three interior angles of every Euclidean triangle sum to 180°.
What is the area of a rectangle measuring 5 cm by 3 cm?
Answer: 15 cm². Explanation: Multiply length by width: 5 × 3 = 15.
How many sides does a hexagon have?
Answer: Six. Explanation: A hexagon is a six-sided polygon.
What is the perimeter of a square with side length 7 cm?
Answer: 28 cm. Explanation: The perimeter is 4 × 7 cm.
What is the volume of a cube with side length 3 cm?
Answer: 27 cm³. Explanation: Multiply its three dimensions: 3 × 3 × 3.
What is the exact circumference of a circle with radius 4 cm?
Answer: 8π cm. Explanation: Circumference is 2π times the radius.
What do you call an angle measuring exactly 90 degrees?
Answer: A right angle. Explanation: A right angle is defined as 90°.
How many meters are in 2.5 kilometers?
Answer: 2,500 meters. Explanation: Each kilometer contains 1,000 meters.
A right triangle has legs of 3 cm and 4 cm. How long is its hypotenuse?
Answer: 5 cm. Explanation: By the Pythagorean theorem, its square is 3² + 4² = 25.
What is the area of a triangle with a base of 10 cm and a perpendicular height of 6 cm?
Answer: 30 cm². Explanation: Area is half the base times the height: 10 × 6 ÷ 2.
Probability and statistics trivia
What is the probability of rolling a 6 on one roll of a fair six-sided die?
Answer: 1/6. Explanation: One of the six equally likely outcomes is a 6.
What is the arithmetic mean of 2, 4, and 6?
Answer: 4. Explanation: Their sum, 12, divided by three values is 4.
What is the median of 3, 8, and 10?
Answer: 8. Explanation: It is the middle value when the numbers are ordered.
What is the mode of 2, 2, 3, 4, and 4, 4?
Answer: 4. Explanation: It occurs three times, more often than any other value.
A fair coin is tossed twice. What is the probability of two heads?
Answer: 1/4. Explanation: Assuming independent tosses, the probability is 1/2 × 1/2.
A bag contains three red balls and two blue balls. One ball is selected at random. What is the probability it is blue?
Answer: 2/5. Explanation: Two of the five balls are blue and each is equally likely to be selected.
What is the range of the data set 5, 9, 12, and 14?
Answer: 9. Explanation: Subtract the minimum from the maximum: 14 − 5 = 9.
A bag contains three red balls and two blue balls. Two balls are drawn at random without replacement. What is the probability that both are blue?
Answer: 1/10. Explanation: The probability is 2/5 for the first blue ball and 1/4 for the second: 2/5 × 1/4 = 1/10.
How many different two-topping combinations can you choose from four distinct toppings if order does not matter and toppings cannot be repeated?
Answer: 6. Explanation: There are 4 × 3 ordered choices; dividing by 2 removes the reversed duplicates.
What is the median of 2, 4, 7, and 11?
Answer: 5.5. Explanation: With four values, average the two middle numbers: (4 + 7) ÷ 2.
Mathematical symbols, constants, and number systems
What mathematical constant is the ratio of a circle’s circumference to its diameter?
Answer: π, or pi. Explanation: The ratio is the same for every Euclidean circle.
What is the decimal value of the binary number 101?
Answer: 5. Explanation: The binary digits represent 1 × 4 + 0 × 2 + 1 × 1.
What does the symbol ≠ mean?
Answer: Not equal to. Explanation: It indicates that two values are different.
What number does the Roman numeral XL represent?
Answer: 40. Explanation: X before L represents 10 subtracted from 50.
Which symbol commonly represents the sum of a sequence of terms?
Answer: Σ, capital sigma. Explanation: Summation notation uses Σ to indicate addition of specified terms.
In decimal notation, which digit occupies the hundreds place in 4,372?
Answer: 3. Explanation: The 3 represents 300.
What is π rounded to two decimal places?
Answer: 3.14. Explanation: This is an approximation; π has a nonterminating decimal expansion.
What is the base of the hexadecimal number system?
Answer: 16. Explanation: Hexadecimal uses sixteen digit symbols, usually 0–9 and A–F.
What does |−7| equal?
Answer: 7. Explanation: Absolute value gives the distance from zero on the number line.
What is the exact value of 10⁰?
Answer: 1. Explanation: Any nonzero number raised to the zeroth power equals 1.
Math history and discoveries
Which ancient Greek mathematician is traditionally associated with the geometry text Elements?
Answer: Euclid. Explanation: Euclid’s Elements organizes geometry and other mathematics into definitions, propositions, and proofs.
What is the name of the sequence 0, 1, 1, 2, 3, 5, in which each later term is the sum of the previous two?
Answer: The Fibonacci sequence. Explanation: Each new term follows the stated addition rule.
Which mathematician’s name is attached to the theorem relating the sides of a right triangle?
Answer: Pythagoras. Explanation: The Pythagorean theorem is named after him, although related knowledge existed in earlier cultures.
Which mathematician is associated with the principle that the upward buoyant force on an object equals the weight of displaced fluid?
Answer: Archimedes. Explanation: The result is known as Archimedes’ principle.
Which mathematician’s surname appears in the name of a famous last theorem proved by Andrew Wiles?
Answer: Fermat. Explanation: The result is known as Fermat’s Last Theorem.
Which mathematician’s name is associated with a famous triangle of binomial coefficients?
Answer: Blaise Pascal. Explanation: Pascal’s triangle bears his name, though the arrangement was known in earlier mathematical traditions.
Which mathematician’s name is used for the coordinate system that locates points using perpendicular axes?
Answer: René Descartes. Explanation: Cartesian coordinates take their name from Descartes.
Which mathematician is associated with the formula V − E + F = 2 for convex polyhedra?
Answer: Leonhard Euler. Explanation: The relationship between vertices, edges, and faces is called Euler’s polyhedron formula.
Which mathematician’s name is attached to a theorem stating that there are infinitely many primes?
Answer: Euclid. Explanation: Euclid’s theorem includes a classical proof that no finite list contains every prime.
Which mathematical field is named in the title of a work by al-Khwarizmi that helped give the field its English name?
Answer: Algebra. Explanation: The term derives from al-jabr, a word in the title of his work.
Logic and reasoning challenge questions
A sequence starts at 2, and each term is obtained by doubling the previous term. What is its fourth term?
Answer: 16. Explanation: The first four terms are 2, 4, 8, and 16.
All squares are rectangles. A particular shape is a square. Must it be a rectangle?
Answer: Yes. Explanation: The stated rule applies to every square.
Three consecutive integers sum to 42. What is the middle integer?
Answer: 14. Explanation: The middle integer is the mean of the three: 42 ÷ 3.
A clock reads 3:00. What is the smaller angle between its hour and minute hands?
Answer: 90 degrees. Explanation: The hands point to 3 and 12, one quarter of a full turn apart.
A number is even and greater than 10 but less than 14. What is it?
Answer: 12. Explanation: It is the only even integer strictly between 10 and 14.
Two people each shake hands once with every other person in a group of four. How many handshakes occur in the whole group, assuming everyone follows that rule?
Answer: 6. Explanation: There are six distinct pairs among four people; each pair shakes hands once.
A farmer has chickens and cows only. There are 10 heads and 28 legs, with each animal having one head and its usual number of legs. How many cows are there?
Answer: 4. Explanation: Ten chickens would have 20 legs; replacing a chicken with a cow adds two legs, so eight extra legs require four cows.
A number increases by 20% and then decreases by 20% of its new value. Is it back to its original value?
Answer: No, unless the original value was zero. Explanation: The final value is 1.2 × 0.8 = 0.96 times the original.
If today is Monday, what day will it be 100 days from today?
Answer: Wednesday. Explanation: 100 leaves a remainder of 2 when divided by 7, so count two days forward.
A box has five pairs of socks, each pair a different color. What is the minimum number of individual socks you must draw without looking to guarantee two of the same color?
Answer: 6. Explanation: The first five could all be different colors; the sixth must match one of them.
How to write and use better math trivia questions
Choose a balanced set for your group
Mix quick number facts with a few calculations and reasoning challenges. Choose questions that fit your group’s background, and allow scratch paper for longer problems. For a paper self-test, prepare a questions-only copy and keep the numbered answers separately.
State assumptions and calculation rules
Specify units, whether a calculator is allowed, and any rounding rule. For probability, explain whether outcomes are equally likely and whether items are replaced after a draw.
Check answers and accept equivalents
Solve each question independently before the quiz. Decide in advance whether equivalent forms, such as 1/2 and 50%, earn the same credit, and check that each question has a clear answer under its stated conditions.
Set clear scoring and timing
Tell participants how much time they have and whether explanations or working earn credit. Apply the same rules to everyone and agree on a way to resolve a disputed answer.
Explore more math quiz formats
Keep your adult math trivia session varied by following the quick-answer rounds with a broader math quiz with answers. If you want participants to judge mathematical claims rather than recall facts, try these true or false math questions. For a round with four possible choices, use these math multiple choice questions.
Ready to create a math quiz?
Choose a mix of familiar facts and harder questions, agree on the timing and scoring, and check answers before the game. To run a short online activity, use NineQuiz and explore Quick Quiz.