Number Series

Missing Number Series

We have seen that a number series is a grouping of numbers, that follows a particular formula or a given rule. There are several types of number series questions that occur in the IBPS and other banking exams and the Missing Number series is one of it. In the Missing Number series, a series is present with a Missing Number or asking you to predict the last term in it. The candidate has to detect and most of the times calculate the value of this Missing Number. The following article will give you many opportunities to read the concepts, get to know about the various tips and tricks and also see many examples. Let us begin.

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Missing Number Series

In the Missing Number series, we see a few examples first. Sometimes, the missing number could be present in the beginning and at other times at the end of the series. As you will see this creates different difficulty levels. The strategy in the missing number series is the same as that of the wrong number series, you have to detect the rule and then use this rule to predict the next number. Following are the tips that can reduce the time consumption to some deal while trying to detect the rule that forms a number sequence:

  • Pick 2/3 terms to test the rule. That means if you have, say 5 given terms, at least pick three of them to test the rule that you want to predict.
  • While choosing the terms to test, select the terms that are the easiest to work with. These include terms that a factor of 2, 3, 5 or 10. Test for common rules like sum of the terms, squares, cubes and other formulae.

Let us see some examples that we shall solve. Remember the more you practice, the more you save on time.

Missing Number

                                                                                                                                         Source: Tiphero

Browse more Topics under Number Series

Solved Examples on Missing Number in Array of Numbers

In the following questions, a number series is given. In each series, a number is missing. The same number is present in the options below. Select the correct option:

Q 1: 32, 40, 24, 16, 24, __

A) 60           B) 12              C) 18            D) 8

Answer: Let us first detect the rule. We will check the rule on at least 2/3rd of our terms. Now let us see the first term is 32 and the third term is 24. Since the third term is smaller than the first one we can speculate that it has been obtained by a rule that has either subtraction or division involved. Similarly, the second term is got from a rule that has either addition or multiplication in it.

We see that 32 + 8 = 40 and 32 – 8 = 24. Now let us check this rule for one more term. We see that 16 + 8 = 24. Therefore this works for more than half of the given numbers. Hence the rule is correct. Therefore the missing number in the series is 16 – 8 =  8. The answer is D) 8.

Q 2: 1, 2, 6, 24, ___

A) 32           B) 64           C) 144              D) 120

Answer: The given sequence has four terms. So the rule must be correct for at least three of them. The first term is 1. The second term is 2 which can either mean 1 is added or 2 has been multiplied. the third term is 6 which can be got from 2 by multiplying it by 3. So thus far we have 1×1, 1×2, 2×3, 6×4, which works perfectly for the series. Thus the rule has been found and the last term will be 24×5 = 120. The answer is thus D) 120.

More Examples Of The Missing Term

In the following examples, a term is missing. Select the missing term from the options that have been provided below:

Q 1: ___, 12, 18, 10, 6, 14, 5, 0, 10.

A) 14          B) 15          C) 16         D) 88

Answer: This might seem intimidating at first but if you see the series carefully, you will notice that it is just like the above series if you take it in reverse. The last three numbers are all multiples of 5. Let us see what we can figure out there. From 5, the next term is 0 which can either be obtained by subtracting 5 from 5 or multiplying it by 0. The last term is 10 which can be obtained from 5 by adding it with 5. Thus we see that the last three follow the rule that [5, 5 – 5, 5 + 5]. The same rule is shown by 10. The triplet containing 10 can be written as [10, 10 -4, 10 + 4]. 10 and 5 have a difference of 5. So the first number has to be 15. Let us check if it satisfies the rule.

The first triplet can be written as 15, 15 -3, 15 + 3. Thus the rule is satisfied and the answer is B) 15.

What many people do in series questions is that they start by using the options directly in the series. This should be used as a last resort. Remember when solving a series, shorten it by selecting 2/3rd of it. In this way, you will be able to simplify a series and solve it easily, saving precious time.

Practice Questions

In the following questions, a number series is given. All the numbers in the series are connected by a rule. one of the numbers is missing. Select the missing number of the series from the numbers given in the options below:

Q 1: 7, 16, 27, 40, ___

A) 45                   B) 55          C) 50         D) 77

Ans: B) 55

Q 2: 80, 119, 166, 221, __

A) 284         B) 380         C) 264          D) 324

Ans: A) 284.

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Shriya NimjeAshishLokeshAkashPinky Choudhary Recent comment authors
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Jagdish
Guest

5 7 31 283 ?

Parth Joshi
Guest
Parth Joshi

4533

ajay jadhav
Guest
ajay jadhav

3967

Priya
Guest
Priya

5×1+2=7
7×4+3=31
31×9+4=283
283×16+5=4533

mahu
Guest

ook

Venu
Guest
Venu

4533

anmol
Guest
anmol

4,8,24,28,84,88,_

Parth Joshi
Guest
Parth Joshi

264

Rahul
Guest
Rahul

4+4=8×3=24+4=28×3=84+4=88×3=264

Ashish
Guest
Ashish

84+100=184or 84+240=324

spy7
Guest
spy7

4+4=8
8×3=24
24+4=28
28×3=84
84+4=88
88×3=264

pavan kalyan
Guest
pavan kalyan

1 5 20 ???

lavanya lakhotia
Guest
lavanya lakhotia

60

anmol
Guest
anmol

1*3+2=5
5*3+5=20
20*3+7=67
can it not be like this???
if not then why?

Sathish
Guest

1×5=5
5×4=20
20×3=60

Saumit
Guest
Saumit

How

srashti
Guest
srashti

60

anmol
Guest
anmol

1*3+2=5
5*3+5=20
20*3+7=67
can it not be like this???
if not then why?

anmol
Guest
anmol

thats 20*3+8=68

Ashish
Guest
Ashish

1×2+3=5×3+5=20×4+7=86

Honey
Guest
Honey

16,4,68,12,?,4,30,1,9 plz reply i need it

ABCD
Guest
ABCD

GAY

Ayushi shukla
Guest
Ayushi shukla

2,3,3,5,10,13,?,43,172,177

Sneha
Guest
Sneha

4,5,5,7,9,13,10__,14

abcd
Guest
abcd

I think
Answer. 15
In series of odd numbers (4, 5,9,10,14) there is addition of 1 and 4 alternately.
And in series of even numbers (5, 7,13,?) There is addition of 2 and 6 alternately.

Janu
Guest
Janu

Find missing teams-1,5,14,?,44

Robin rathi
Guest
Robin rathi

Find the missing number of this series
60,50,60,90,41,_?

Options 1. 12
2. 18
3. 25
4. 30
5. none this above

Rohith
Guest
Rohith

26,4,20,10,14,16,8,22,2,28

Paulo
Guest

____,360,000,000,____, 389,000,000,____, 420,000,000

Sune Pedersen
Guest
Sune Pedersen

37 52 93 75 29 ? what is the math behind this

Sonali sahu
Guest
Sonali sahu

2,1,0,-3,-24,? Find the next number

Pinky Choudhary
Guest

Upper line 3 5 8 mid line 6 10 32 lower line 9 ? 50 me missing no. Kya h

Akash
Guest
Akash

94 101 115 136 164 ?

Ashish
Guest
Ashish

199

Lokesh
Guest
Lokesh

QID : 426 – In the following question, select the
missing number from the given alternatives.
41, 83, 167, 335, 671, ?
Options:
1) 1297
2) 1343
3) 1447
4) 1661

Ashish
Guest
Ashish

1343

Shriya Nimje
Guest
Shriya Nimje

50,50,54,72,?,220

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