Verbal Reasoning : Complete the Letter Series / Sequence (Type L)

The Letter Series question type requires you to work out the final pair of letters in the sequence. You have to do this by looking at the previous pairs in the sequence and identifying the pattern, relationship or rule they follow from pair to pair.

Although you are working with letters here its important to understand that the sequence will follow a mathematical process. This means that the change to both or either letter will either go forward or backward a certain number of positions. This should be your focus and you should ask yourself – how many positions is either letter moving to get to the next pair?

After working out the pattern / relationship you must then fill in the last pair of letters in the sequence using your pattern. You are the one coming up with the pattern, and you will use the previous pairs in the sequence to work out what hat is, this is similar to Number Relationships.

The Letter / Alphabet Series question type really focuses in on testing the following skills:

• Analytical skills
• Ability to understand and work out patterns and trends
• Step by step approach – going from pair to pair
• Identifying change individually and collectively
• Being able to provide the next number or solution by analysing previous knowledge
• Working out a rule in numbers and applying it to a different format (letters / alphabet)
• Understanding of how things can be similar and follow a way of doing things even if they look different

Just by looking at the skills being tested this question centers around analysis. You need to be able to look at information some or most of which may not make sense at first glance. Now the issue isn’t to do with the final pair or the solution, but it is about getting confident in understanding how all the other pairs came about.

Through a process you need to be able to step back and, from a broader view, see how all these individual pairs of information relate to each other and how change occurs. The ability to apply this process will then give you the ability to work out the final pair in the sequence.

The way you make them relate to each other is through a mathematical / number relationship. You then have to take this relationship and apply it in the format of the information – which is moving through the alphabet. So it is not only about working out the rule on how the letters have changed, but also understanding how the rule needs to be applied.

What do Letter Series Questions Look Like?

As you can see from the Gaggle example below, the Letter Series question is in the following format:

• General example with instructions
• Group of 3 to 5 pairs per questions
• An empty pair, usually shown by underscores ( __ ) which is the pair you need to work out
• 1 mark per question
• Option to write on the line or select from the multiple choice on the answer sheet

How do I answer this question?

Before we get into a working example of the Letter Series it is important that you know that there is a process that you can apply to get you to an answer. This question type relies on your ability to apply that process, which will help you identify the pattern. When we are looking for patterns, all we want to do is understand how the sequence is changing from pair to pair.

Once you know what the pattern is, and how the letters change from the existing sequence, you can then apply the pattern to future pairs in the same sequence.

You need to be comfortable understanding that the way things changes are based on numbers, meaning move forward by 2 or move back by 2. But the thing that actually changes is the letter. And that the pattern can be anything, it is up to you to figure it out by applying a trial and error process, where you come up with a potential solution and then test it out to see if it works.

Remember, the main focus of this question is testing your ability to work out the pattern, the final result will be the last pair.

For any question that you may come across the following will almost always apply, so use them to create a process:

1. A pattern shows how many letters to move forward or back in the form of plus or minus
2. The first and second pair may not always show you the whole pattern – but you should always start by working how many moves you need to make to get from pair 1 to pair 2
3. What happens to the first letter may not happen to the second
4. The position of the letter e.g. first or second of each pair is always linked, a letter in position 1 will not change a letter in position 2
5. What happens to the first letter may be the opposite to the second letter in a pair e.g. first letter is +2 but second letter is -2
6. The first and second letters in the pair may change individually e.g. the first letter may change by adding 1 whilst the second letter may change by adding 3
7. Changes in each pair can be multiplied
8. Changes in each pair can occur in odd or even orders e.g. +1, +3, +5 or +2, +4, +6
9. Look for a regular pattern , which is where the same thing happens between each pair
10. Look for an irregular pattern, which is where different things could happen between each pair e.g. first pair is add, second pair is minus, third pair is add, fourth pair is minus
11. Changes between pairs can happen in increasing or decreasing number order e.g. +1, +2, +3, +4, +5 or -5, -4, -3, -2, -1
12. Always check the change occurring across the sequence in order to spot patterns

The above rules will help you understand the questions you need to begin asking yourself when you see one of these letter series questions. Ask yourself is the change from pair to pair an addition of 3, or a subtraction of 1. Or whether you need to look at the change per letter in each pair and whether from pair to pair it is increasing or decreasing.

Work through the sequence and write down the change that’s happening – count how many letters the first letter in pair 2 is from the first letter in pair 1, and make a note of it.

Working Example

Now we have our fundamentals, which will guide our process and allow us to ask the right questions, lets apply it to the working example below:

Question 1:

DV, EU, CW, FT, ( _ _ )

Lets try to work this out by applying the checklist from above (which is now our process). We might not need to go through the whole list, but its enough to make sure we cover as much ground as possible.

So first of all I want to understand the differences in the pairs and how they are changing, this will give me my pattern.

I do this by lookin at pair 1 (DV) and seeing how much I need to move to get to pair 2 (EU).

So lets work that out. I already know that any changes to the first letters only apply to the first letter of each pair and any changes to the second letter only apply to the second letter of each pair, so I can look at them individually.

To get from pair 1 letter 1 (D) to pair 2 letter 1 (E) I need to plus 1 – so lets write that down somewhere.

Now from pair 1 letter 2 (V) to get to pair 2 letter 2 (U) I need to minus 1.

So far the pattern is +1 and -1.

Now lets work through the rest of the sequence to understand whether this is a regular or irregular pattern, we do this by checking how many moves we need to make to go from EU to CW.

From E to C it is – 2.

From U to W it is + 2.

So now we can see the pattern is changing, it looks like this:

1. Pair 1 Letter 1 move is + 1 / Pair 1 Letter 2 move is – 1
2. Pair 2 Letter 1 move is – 2 / Pair 2 Letter 2 move is + 2

In case it is difficult to tell, we can see 3 things these are:

1. What happens to the first letter, the opposite happens to the second letter
2. For each pair the opposite order happens from the pair before e.g. if pair 1 had an addition happen to letter 1 then pair 2 would have a subtraction
3. They are going up normal number order e.g. 1, 2, 3

Now we have spotted the pattern, lets carry on and see if going from CW to FT follows the pattern.

So to go from C to F I need to add 3.

To go from W to T I need to minus 3.

So we have proven the pattern we have noticed which is:

1. The opposite operation (plus or minus) happens to the letters from the previous pair.
2. They are going up in number order e.g. 1, 2, 3
3. The operation that happens to the first letter e.g. addition, the opposite happens to the second letter e.g. subtraction

By applying our pattern we can work out the final unknown pair. So we know that the opposite operations happen to the previous pair, so in the unknown pair for letter 1 we need to minus and letter 2 we need to plus.

We also know the changes are going up in order, we have gotten as far as 3, so the next change will be for 4.

Lets do this, to work out the next pair from FT we need to minus 4 from F (move by 4 places) which is B.

Then for the second letter T we need to add 4 places which gets us to X.

And thats it, the unknown pair is BX and we have also worked out the pattern!

REMEMBER: Do not include the letter as 1, what we mean by this is when working out 4 places from T don’t think T is our first move. The next letter which is U is our first move. So if you are counting on your fingers count your first finger when you count U.