Number Series Questions for CAT with Answers PDF

The given series follows a pattern as given below:
210 ÷ 10 = 21
21 × 9 = 189
189 ÷ 10 = 18.9
18.9 × 9 = 170.1
170.1 ÷ 10 = 17.01
So, the missing number is 18.9.

First term – 10
Second term – 10 × 1 + 1 = 11
Third term – 11 × 2 + 2 = 24
Fourth term – 24 × 3 + 3 = 75
Fourth term – 75 × 4 + 4 = 304
Missing term – 304 × 5 + 5 = 1525

The given series follows the pattern as shown below:
18 x 1 + 1.5 = 19.5
19.5 x 2 + 2.5 = 41.5
41.5 x 3 + 3.5 = 128
128 x 4 + 4.5 = 516.5
516.5 x 5 + 5.5 = 2588
2588 x 6 + 6.5 = 15534.5
Therefore, 513.5 is the wrong term in the series.

The given series follows a pattern as shown below.
11 x 5 - 10 = 55 - 10 = 45
45 x 5 - 10 = 225 - 10 = 215
215 x 5 - 10 = 1075 - 10 = 1065
1065 x 5 - 10 = 5325 - 10 = 5315
5315 x 5 - 10 = 26575 - 10 = 26565
Therefore, 1165 is the wrong term in the given series.

The given series follows the pattern as shown below.

Therefore, 134 is the wrong term in the given series.

The given series follows a pattern as shown below.
8 x 2 - 1 = 16 - 1 = 15
15 x 3 - 2 = 45 - 2 = 43
43 x 4 - 3 = 172 - 3 = 169
169 x 5 - 4 = 845 - 4 = 841
841 x 6 - 5 = 5046 - 5 = 5041
5041 x 7 - 6 = 35287 - 6 = 35281
So, the wrong term in the given series is 41.

The pattern is as follows.
1³ = 1 
2² = 4
3³ = 27
4² = 16
5³ = 125
6² = 36
7³ = 343 

The given series is an alternate series. Odd series is double of consecutive prime numbers.
i.e.
2 × 2 = 4
3 × 2 = 6
5 × 2 = 10
7 × 2 = 14

Even series is as:

4²/2 = 8

6²/2 = 18

10²/2 = 50

14²/2 = 98

Here, the pattern is addition of powers of 3 to the previous terms to get the next term.
First term – 2
Second term – 2 + 3 = 5
Third term – 5 + 9 = 14
Fourth term – 14 + 27 = 41
Fifth term – 41 + 81 = 122 
Missing term – 122 + 243 = 365

First term – 15
Second term – 15 + 22 = 19
Third term – 19 + 32 = 28
Fourth term – 28 + 42 = 44
Fifth term – 44 + 52 = 69
Missing term – 69 + 62 = 105

First term – 6
Second term – 6 × 2 + 5 = 17
Third term – 17 × 2 + 5 = 39
Fourth term – 39 × 2 + 5 = 83
Fifth term – 83 × 2 + 5 = 171
Missing term – 171 × 2 + 5 = 347

Series is as follows.
(7 + 5) × 5 = 60,
(60 + 5) × 5 = 325,
(325 + 5) × 5 = 1650,
(1650 + 5) × 5 = 8275
Therefore, option (3) is the correct answer.

Series is as follows.
19 × 17,
17 × 13,
13 × 11,
11 × 7,
7 × 5,
5 × 3
Multiplication of prime numbers is done in decreasing order.
Therefore, option (1) is the correct answer.

2³ - 1 = 7
3³ - 1 = 26 (Not 28)
4³ - 1 = 63
5³ - 1 = 124
6³ - 1 = 215
7³ - 1 = 342
8³ - 1 = 511
Hence, 28 is a wrong number. The correct number is 26.