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How to Solve Number Series: Example Questions & Tips – 2024

numerical series in aptitude tests

Numerical sequence questions test your ability to recognize patterns and manipulate numbers using a variety of mathematical functions. Whether you’ll have to fill in the missing numbers or rearrange the terms according to the rule, these series number tests will keep you on your toes.

Number series questions generally appear on a wide variety of numerical reasoning tests. Below, you’ll find a short description of the different kinds of series of numbers you might encounter as well as several examples of each number series. Try your hand at some of the questions below, and watch our helpful tutorial video to start preparing for your psychometrics exam immediately.


What Are Number Series?

A number series is a list of numbers whose placement is determined according to a certain rule. That rule may be as simple as adding or multiplying by one factor, or it may involve a complex series of steps. Some series even require two separate rules, which are employed alternatingly.


How to Solve Series Questions?

Your job is to determine the series’ rule by analyzing the numbers given to you. Sometimes the answer will be self-evident, but most of the time it won’t be. If your only method of solving problems is trial-and-error, you’ll waste a lot of time guessing.

Thankfully, series questions follow predictable patterns. If you’re familiar with the five most common patterns for number series, then you’ll quickly be able to eliminate possibilities until you come to the correct answer.


Simple Arithmetic Number Series

In an arithmetic number series, each number either increases or decreases by the same amount each time. These series are relatively easy to spot. You should always check to see whether the series is increasing or decreasing by a constant factor before moving on to other possibilities.

Here are two examples of arithmetic number series.

7, 11, 15, 19, 23, 27, 31, 35, 39…

21, 15, 9, 3, -3, -9, -15, -21…


Dynamic Arithmetic Series

In a dynamic arithmetic series, you’ll still be either adding or subtracting, but the factor will change each time. For example, you might add one to the first number to get the second number and then two to the second number to get to the third number. Alternatively, you might be adding one number to the odd numbers in the series and a different number to the even numbers in the series. Refer to the examples below to see how dynamic arithmetic series works in practice.

1,2, 4, 7, 11, 16, 22, 29, 37, 46, 56…

3, 9, 8, 7, 13, 5, 18, 3, 23, 1, 28, -1…


Geometric Series

A geometric series, as opposed to an arithmetic series, deals with multiplication and division.

2, 6, 18, 54, 162…

100, 50, 25, 12.5, 6.25…


Complex Series

Complex series use a two-step rule. For instance, a complex series might use both arithmetic and geometric principles. If the numbers seem to be spaced apart at random intervals but increase continuously, then you might have a complex series.

1, 5, 13, 29, 61…

Here the rule is 2x+3. You must double each number and then add three to find the next number.


Advanced Series

Advanced series are creative and somewhat unpredictable. They might use exponents or other mathematical functions. They might also be dynamic. Take the Fibonacci sequence, for example. In the Fibonacci sequence, each number is the sum of the previous two.

0, 1, 1, 2, 3, 5, 8, 13, 21, 34

Unfortunately, advanced series have no rules. If you’re taking a psychometric exam, you might find that advanced series throw you off. If you know the series is neither an arithmetic nor a geometric series, then you might have to start thinking outside the box.

How to Prepare for a Number Series Test?

If you’re a graduate or job-seeker preparing for a pre-employment aptitude assessment, you’ll want to make sure you can recognize all of the standard series. You shouldn’t have to spend much time at all identifying arithmetic or geometric series regardless of whether they’re simple or dynamic. That way, you have the time to work out a complex number series.

When you do come to an advanced number series, there are no set rules. (Tip: If you’ve ruled out all other possibilities, then check to see how each term relates to the two preceding it.)


Final Thoughts on Reasoning Series:

If you’re still worried about your screening test, then take a look at the helpful video tutorial. When you’re done, click over to our online questions tab and check out the number series examples we created just for you.


Helpful Video:


Free Sample Questions:

  1. Find the missing number in the following series.
    3, 4, 0, 8, X, 16, -6, 32
  2. Finish the series below.4, 2, -4, -22, -76…



  1. -3
  2. -238: (3X-10)