Number-series-example16

 

Find the missing number in the following set:

3, 10, 24, x, 108, 220 

Scroll down to see the answer

 

 

 

 

 

Correct answer  is 52

 

3, 10, 24, x, 108, 220 

We can solve it in 2 ways.

Α way

 

 Calculate the differences between 

those that are next to each other.

10-3=7

24-10=14

108-52=56

220-108=112

 

The number series of the differences is:

7,14, x, 56, 112

Notice that every term is multiple by 2

7X2=14        56X2=114

The number series is GP with common ratio 2

So the number series of differences is:

7, 14, 28, 56,  112

 

Therefore the missing number is:

24+28=52

 

B way

 The rule is as follows:

 add 2 to the previous number then multiply times 2.

(3+2)x2=10

(10+2)x2=24

(24+2)x2=52

(52+2)x2=108

(108+2)x2=220

Correct answer is:

52

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Number-series-examplequestions-15

 

 

 

Number series are central to all bank exams

 Example questions

with answers and detailed explanations.

 

Select the number that can replace the question mark (?)

 in the following series.

3, 3, 9, 45,  315,  ?

 A) 945    B) 1050   C) 2835  D) 2205

 

Corect answer is C

EXPLANATION

 

3X1=3

3X3=9

9X5=45

45X7=315

We observe that the numbers by which they are multiplied are
1,3,5,7
It is an arithmetic progression with difference  2 

The next term is 7+2=9

So the missing number in the given series is:

315  x 9=2835

Correct answer is C

 

 You can go to the best preparation

 detailed explanations tips and tricks 

to learn step by step 

answer every question in the banking exams

 

 Offer   € 19.90
  

Number series-practice-puzzle 591

 Number series questions and answers for all competitive exams.

  Puzzle 591

 By Panos Kalliantasis

 

How to solve number sequences.

Examples with detailed explanations.