Whether you are preparing for RBI Grade B or IBPS PO or any other banking examination, number series is a topic that cannot be avoided. They might appear confusing but in reality are not; in fact, you can answer number series questions easily by simply understanding the pattern of the questions that appear. Therefore, number series is a topic from which one can expect anywhere between 3-5 questions in the examination, and when solved correctly, even 1 question can make the difference between selection and rejection. In this blog post, we shall see some tricks to help us solve Number Series problems easily. While this blog post is helpful for RBI Grade B aspirants, the concepts are similar for all the banking examinations.
Number Series Types of Patterns
There are four major patterns when it comes to questions from the number series topic; those include –
- Squares of Numbers (and Cubes of Numbers)
- Prime Numbers
- Combination of (1), (2), and/or (3)
In bank examinations, you can expect difficult questions especially since it is for RBI Grade B or any regulatory body examinations.
Number Series How to Identify Patterns
Since number series questions are all about identification of patterns, the best approach in this case would be determine the patterns in the questions because that can help you eliminate the choices or answer options which are not relevant to the question and help you find the answer by elimination. Some tricks that you can keep in mind when solving or attempting number series questions have been given below.
- Track the difference between the numbers in the pattern and see if there is any kind of pattern that stands out between the consecutive numbers. In this case, you may have either of the 2 inferences: (1) if the difference tends to go up or down rapidly, then it might be a case of squares, cubes, or multiplication, or (2) if the difference is not growing as fast, then it might be a case of addition/subtraction.
- Understand that in any case there will be sub-patterns in the number series; you will need to practice more questions to see what kind of sub-patterns may be visible or formed.
Number Series Solved Examples
- Find the next number on the series: 243, 5, 81, 15, 27, 45, 9, ?
In this case, you need to track the pattern by breaking the numbers down into constituents:
243 = 3*3*3*3*3 =3^5
5 = 5*1 = 5
81 = 3*3*3*3 = 3^4
15 = 5*3 = 15
27 = 3*3*3 = 3^3
45 = 5*3*3 = 5*9
9 = 3*3 = 3^2
So, the pattern is: 3^5, 5(1), 3^4, 5(3), 3^3, 5(3^2), 3^2, 5(3^3)
So, 5(3^3) = 5(27) = 135
Therefore, the solution is 135.
Consider another question.
- Find the next number on the series: 5, 50, 45, 450, 445, ?, 4445
This question might have bigger numbers, but it is still doable. See how —
First number is 5
Second number is 50 which is 5 x 10
Third number is 45 which is 50 – 5
Fourth number is 450 which is 45 x 10
Fifth number is 450 – 5
Sixth number is ?
Seventh number is 6th number – 5 again
So the pattern goes on like: x10, -5, x10, -5, x10, -5 ….
So, by this logic, the 6th number should be x10 the 5th number which in turn would be 445, so the answer is 445*10 = 4450
Therefore, the answer is 4450.
Number Series Tips to Remember
Therefore, it can be seen that if the pattern to the questions is known then it becomes easy to solve the number series questions in the examination. However, as guideline, remember the following:
- In the exam, if it takes you longer than 1 minute to determine the pattern, leave the question because it is a waste of time.
- Do not attempt to rush through answers. If you cannot determine a pattern with 100% confidence, do not attempt the question at all.
- Do not attempt decimal questions unless you have 100% sure about the pattern.
- Start with the addition/subtraction and then move on to multiplication/division when determining the patterns.
- Keep an eye out for prime numbers, they do not multiply/divide by anything other than themselves so, when they are present you should almost always start with addition/subtraction to see if there is a pattern.
All the Best!