Number Series
Number Series
Q. #6541 (CAT-I)
Find the incorrect number in the sequence:
8, 13, 21, 32, 47, 63, 83
The difference between consecutive terms increases by 3:
8 + 5 = 13
13 + 8 = 21
21 + 11 = 32
32 + 14 = 46 (given as 47)
46 + 17 = 63
63 + 20 = 83
• Hence, the incorrect term is 47.
Number Series
Number Series
Q. #6540 (CAT-I)
Identify the wrong number in the following series:
19, 28, 39, 52, 67, 84, 102
Let us examine the differences between successive numbers:
19 + 9 = 28
28 + 11 = 39
39 + 13 = 52
52 + 15 = 67
67 + 17 = 84
84 + 19 = 103 (instead of 102)
• Therefore, 102 is the wrong number in the series.
Number Series
Number Series
Q. #6539 (CAT-I)
Find the missing term in the series: 3, 5, 9, ?, 33, 65
The terms follow the pattern of powers of 2 plus 1 (2ⁿ + 1):
2¹ + 1 = 3
2² + 1 = 5
2³ + 1 = 9
2⁴ + 1 = 17
2⁵ + 1 = 33
2⁶ + 1 = 65
• Hence, the missing term is 17.
Number Series
Number Series
Q. #6538 (CAT-I)
Find the missing number in the given series:
19, 9, 28, 37, 65, ?
A.
99
B.
97
C.
102
D.
113
Each term from the third term onward is the sum of the preceding two terms:
19 + 9 = 28
9 + 28 = 37
28 + 37 = 65
37 + 65 = 102
• Thus, the missing number is 102.
⚡ Practice with real exam timer and negative marking?
Attempt 100-Question Sunday Mega Mock Tests with Live State Rankings.
Number Series
Number Series
Q. #6537 (CAT-I)
Find the missing number in the following series:
1, 3, 6, 11, 18, ?
The differences between consecutive numbers are consecutive prime numbers:
1 + 2 = 3
3 + 3 = 6
6 + 5 = 11
11 + 7 = 18
18 + 11 = 29
• Therefore, the missing term is 29.
Number Series
Number Series
Q. #6536 (CAT-I)
Find the missing term in the given sequence:
5, 13, 40, 104, ?
A.
217
B.
229
C.
259
D.
279
The differences between consecutive terms are cubes of consecutive integers:
5 + 2³ = 5 + 8 = 13
13 + 3³ = 13 + 27 = 40
40 + 4³ = 40 + 64 = 104
104 + 5³ = 104 + 125 = 229
• Thus, the next number in the series is 229.
Number Series
Number Series
Q. #6535 (CAT-I)
What will replace the question mark (?) in the following series?
2, 3, 6, 7, 14, 15, ?
The pattern alternates between adding 1 and multiplying by 2:
2 + 1 = 3
3 × 2 = 6
6 + 1 = 7
7 × 2 = 14
14 + 1 = 15
15 × 2 = 30
• Hence, the missing number is 30.
Number Series
Number Series
Q. #6534 (CAT-I)
Find the missing number in the series: 1, 2, 6, 12, 36, 72, ?
A.
108
B.
144
C.
180
D.
216
The pattern follows alternating multiplication by 2 and 3:
1 × 2 = 2
2 × 3 = 6
6 × 2 = 12
12 × 3 = 36
36 × 2 = 72
72 × 3 = 216
• Therefore, the next number is 216.
Number Series
Number Series
Q. #6533 (CAT-I)
Find the missing number in the following series: 219, 211, 204, 198, ?, 189
A.
196
B.
193
C.
192
D.
190
The consecutive differences decrease by 1 at each step:
219 - 8 = 211
211 - 7 = 204
204 - 6 = 198
198 - 5 = 193
193 - 4 = 189
• Therefore, the missing term is 193.
Number Series
Number Series
Q. #6532 (CAT-I)
Find the wrong number in the following series: 6, 11, 16, 20, 26
The series has a constant difference of +5 between consecutive terms:
6 + 5 = 11
11 + 5 = 16
16 + 5 = 21 (given as 20)
21 + 5 = 26
• Therefore, 20 is the incorrect number in the series.
Number Series
Number Series
Q. #6531 (CAT-I)
Find the wrong number in the given sequence: 331, 482, 551, 263, 383, 242, 111
A.
263
B.
482
C.
383
D.
242
In each valid number, the product of the first (hundreds) and third (units) digit equals the middle (tens) digit:
3 × 1 = 3 in 331
4 × 2 = 8 in 482
5 × 1 = 5 in 551
2 × 3 = 6 in 263
2 × 2 = 4 in 242
1 × 1 = 1 in 111
• For 383, 3 × 3 = 9 ≠ 8. Therefore, 383 is the wrong number.
Number Series
Number Series
Q. #6530 (CAT-I)
Identify the incorrect number in the sequence: 7, 28, 63, 124, 215, 342
A.
28
B.
63
C.
124
D.
342
The pattern follows n³ - 1 for n = 2, 3, 4, 5, 6, 7:
2³ - 1 = 8 - 1 = 7
3³ - 1 = 27 - 1 = 26 (given as 28)
4³ - 1 = 64 - 1 = 63
5³ - 1 = 125 - 1 = 124
6³ - 1 = 216 - 1 = 215
7³ - 1 = 343 - 1 = 342
• Hence, the wrong number in the series is 28.
Number Series
Number Series
Q. #6529 (CAT-I)
Find the wrong number in the given series: 2, 5, 10, 17, 26, 37, 50, 64
The series represents n² + 1 for consecutive integers starting from 1:
1² + 1 = 2
2² + 1 = 5
3² + 1 = 10
4² + 1 = 17
5² + 1 = 26
6² + 1 = 37
7² + 1 = 50
8² + 1 = 65 (instead of 64)
• Thus, 64 is the incorrect term.
Number Series
Number Series
Q. #6528 (CAT-I)
Find the next term in the following series: (2, 3), (3, 5), (5, 7), (7, 11), (11, 13), ?
A.
(13, 15)
B.
(13, 19)
C.
(13, 17)
D.
(15, 17)
Each pair consists of two consecutive prime numbers (pₙ, pₙ₊₁):
First pair: (2, 3)
Second pair: (3, 5)
Third pair: (5, 7)
Fourth pair: (7, 11)
Fifth pair: (11, 13)
• Following consecutive primes after 11 are 13 and 17, so the next pair is (13, 17).
Number Series
Number Series
Q. #6527 (CAT-I)
Find the missing number in the series: 1, 1.5, 2.5, 4, ?, 8.5, 11.5
A.
5.0
B.
6.0
C.
5.5
D.
6.5
The difference between consecutive terms increases by 0.5 each step:
1 + 0.5 = 1.5
1.5 + 1.0 = 2.5
2.5 + 1.5 = 4.0
4.0 + 2.0 = 6.0
6.0 + 2.5 = 8.5
8.5 + 3.0 = 11.5
• Therefore, the missing value is 6.0.