Solved examples of number series in Quantitative aptitude As we know, questions related to number series are very important in Quantitative aptitude s

Examples with Solutions

Example1: In the following given series, find out the wrong number.
1, 3, 10, 21, 64, 129, 356
Solution: As i have discussed in previous session, operations applied on series can be: Addition or subtraction, multiplication or division, squaring or cubing and combination of any.

Series 1 3 10 21 64 129 356 Difference 2 7 11 43 65 227
By studying the above series, you’ll come to know that, this is a combination of operations. Operation used is discussed as follows:
Alternately using: $(\times 2+1)and(\times 3+1)$
$1\times 2+1=3$

$3\times 3+1=10$

$10\times 2+1=21$

$21\times 3+1=64$

$64\times 2+1=129$

$129\times 3+1=388$
Therefore, last number of series is wrong i.e.356
Example2: Find the next number of the following series:
672, 560, 448, 336, 224,?
Solution: Check out the difference of each number first:
Series: 672 560 448 336 224 Difference: 112 112 112 112
Difference between all the terms is same i.e. 112
Therefore, next term will be $=224-112=112$ Ans
Example3: Find the next term of following series: 82, 67, 54, 43, 34
Solution: The operation used in series is discussed as follow: $9^2+1=82$

$8^2+3=67$

$7^2+5=54$

$6^2+7=43$

$5^2+9=34$
Continuing like this;
$4^2+11=27$
Therefore, 27 is the next term.
Example4: What should come in place of question mark?
1721, 2190, 2737, 3368,?
Solution: As we can see, first term is approximately equal to the cube of 12, so firstly we will try to solve it with the cubes.
$(12{)}^3-7=1721(13{)}^3-7=2190(14{)}^3-7=2737(15{)}^3-7=3368$
Now you can find, that there is some pattern. So, continuing like this, we get $(16{)}^3-7=4089$ Ans
Example5: Find the next term of following series:
8, 24, 12, 36, 18, ?
Solution: Relation between the terms is as follows:
$8\times 3=24$
$24/2=12$
$12\times 3=36$
$36/2=18$
Continuing like this: $18\times 3=54$
Therefore, next term is 54
Example 6: Find the next term of the following series:
47, 33, 21, 11, ?
Solution: The pattern used in the series is as follows:
$7^2-2=47$

$6^2-3=33$

$5^2-4=21$

$4^2-5=11$ By continuing, we get $3^2-6=3$ Therefore, 3 is the next term.
I will soon update the questions for your practice.