Number Sequence Quiz: Find the Next Number in 10 Series

This number sequence quiz asks you to find the next number in ten different series, including square numbers, cube numbers, prime numbers, triangular numbers, factorials, doubling patterns and the strange look-and-say sequence studied by John Conway, with a short look at Fibonacci and Pascal's triangle. Spot the rule, then choose the answer.

Start Number Sequence Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 90 Seconds

Question 1 / 10 Time: 90s

Squares
What comes next: 1, 4, 9, 16, 25, ...?
Primes
What comes next: 2, 3, 5, 7, 11, 13, ...?
Triangular
What comes next: 1, 3, 6, 10, 15, ...?
Powers
What comes next: 3, 9, 27, 81, ...?
Differences
What comes next: 100, 95, 85, 70, 50, ...?
Factorials
What comes next: 1, 2, 6, 24, 120, ...?
Rules
What comes next: 2, 5, 11, 23, 47, ...?
Cubes
What comes next: 1, 8, 27, 64, ...?
Alternating
What comes next: 7, 14, 12, 24, 22, ...?
Look and say
What comes next in the look-and-say sequence: 1, 11, 21, 1211, 111221, ...?

Explanations: answer key for all 10 questions

Q1: What comes next: 1, 4, 9, 16, 25, ...?
Answer: 36
These are square numbers: 1 times 1, 2 times 2, 3 times 3 and so on. The next one is 6 times 6, which is 36.
Q2: What comes next: 2, 3, 5, 7, 11, 13, ...?
Answer: 17
These are prime numbers, which can be divided only by 1 and themselves. After 13, the next prime is 17, because 15 is 3 times 5.
Q3: What comes next: 1, 3, 6, 10, 15, ...?
Answer: 21
The gaps grow by one each time: plus 2, plus 3, plus 4, plus 5 and then plus 6. These are called triangular numbers.
Q4: What comes next: 3, 9, 27, 81, ...?
Answer: 243
Each number is three times the one before. 81 times 3 is 243, which is also 3 to the power of 5.
Q5: What comes next: 100, 95, 85, 70, 50, ...?
Answer: 25
The amount taken away grows by five each time: 5, 10, 15, 20 and then 25. So 50 minus 25 gives 25.
Q6: What comes next: 1, 2, 6, 24, 120, ...?
Answer: 720
Each number is multiplied by the next whole number: times 2, times 3, times 4, times 5 and then times 6. These are called factorials.
Q7: What comes next: 2, 5, 11, 23, 47, ...?
Answer: 95
The rule is double the number and add one. 47 doubled is 94, and adding one gives 95.
Q8: What comes next: 1, 8, 27, 64, ...?
Answer: 125
These are cube numbers: 1, 2, 3 and 4 multiplied by themselves three times. The next is 5 times 5 times 5, which is 125.
Q9: What comes next: 7, 14, 12, 24, 22, ...?
Answer: 44
The pattern takes turns: double, then subtract 2. After 22 comes another doubling, which gives 44.
Q10: What comes next in the look-and-say sequence: 1, 11, 21, 1211, 111221, ...?
Answer: 312211
Each term describes the one before. 111221 is three 1s, two 2s and one 1, which is written 312211.

Number Sequence Quiz – Finding the Hidden Rule

A number sequence is a list of numbers that follows a rule. Number sequence questions appear in school math tests, aptitude tests and IQ-style quizzes because they test how quickly you can spot patterns. The key is to look for the rule that turns one number into the next.

Start by looking at the differences between numbers. If the gaps are the same, the rule is adding or subtracting a fixed amount. If the gaps themselves grow, as in triangular numbers, look at the gaps between the gaps. If the numbers grow very fast, try multiplying or dividing instead. Some sequences alternate between two rules, such as double then subtract two.

Many famous sequences have special names. Square numbers come from multiplying a number by itself, and cube numbers from multiplying it three times. Prime numbers can be divided only by 1 and themselves, and mathematicians have known since Euclid that there are infinitely many. Factorials grow amazingly fast: 10 factorial is more than 3.6 million.

The Fibonacci sequence, named after the Italian mathematician Leonardo of Pisa, adds the two previous numbers to get the next. It appears in sunflower seeds and pinecones. Triangular numbers can be found in Pascal's triangle, a famous number pattern studied by Blaise Pascal.

The look-and-say sequence is a playful puzzle. Each term describes the previous one aloud. British mathematician John Conway studied it in the 1980s and discovered how quickly its terms grow.

With practice, you will start to recognize these patterns instantly, which makes number puzzles faster and more fun.

What This Quiz Teaches

This quiz is perfect for math fans, students and puzzle lovers.

How to find the rule in a number sequence
Square, cube and triangular numbers
Prime numbers and factorials
Doubling and alternating patterns
The look-and-say sequence of John Conway
Fibonacci numbers and Pascal's triangle

Quick Facts About Number Sequences

The Online Encyclopedia of Integer Sequences lists more than 370,000 sequences.
The largest known prime numbers have millions of digits.
Triangular numbers count the dots in triangles of growing size.
Fibonacci introduced Hindu-Arabic numerals to many Europeans in 1202.
Square numbers always end in 0, 1, 4, 5, 6 or 9.
Sequence puzzles are common in job aptitude tests.