Series / Coding-Decoding | IAF AFCAT Past Year Papers PDF Download

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Series/Coding-Decoding C-13
1. Which number comes next in this series ? [2011-II]
1 4 7 10 13 16
(a) 17 (b) 1 9
(c) 21 (d) None of these
2. Which number comes next in this series ? [2011-II]
0 1 3 6 10 15
(a) 19 (b) 2 1
(c) 26 (d) 3 2
3. Look at the series 36, 34, 30, 28, 24, ..... what number should
come next ? [2011-II]
(a) 20 (b) 2 2
(c) 23 (d) 2 6
4. Look at the series 22, 21, 23, 22, 24, 23 ..... what number
should come next ? [2011-II]
(a) 22 (b) 24
(c) 25 (d) 26
5. Look at the series 53, 53, 40, 40, 27, 27 ..... what number
should come next ? [2011-II]
(a) 12 (b) 14
(c) 27 (d) 53
6. Look at the series 8, 22, 8, 28, 8 ..... what number should
come next ? [2011-II]
(a)9 (b) 3 4
(c) 29 (d) 3 2
7. Look at the series 31, 29, 24, 22, 17 ..... what number should
come next ? [2011-II]
(a) 15 (b) 1 4
(c) 13 (d) 1 2
DIRECTIONS (Qs. 8 – 10) : Complete the series [2014-I]
8. A, B, D, G , ?,  P
(a)I (b) J
(c)K (d) L
9. Z , S , W , O , T, K, Q, G , ?, ?
(a) N, D (b) N, C
(c) O, C (d) O, D
10. BCD , RQP , LMN, TS?
(a)U (b) V
(c)R (d) T
11. If A = C , B = D , C = E and so on, code the following:
‘STUDENT’ [2014-I]
(a) VW VF GP V
(b) UUWFGPV
(c) U VWFGPV
(d) U VVF GPV
12. If A = Z, B = Y and so on, code the following: [2014-I]
‘EDITOR’
(a) VWR GLI (b) VW R G VI
(c) VW VG LI (d) V WR LL I
DIRECTIONS (Qs. 13-14) :  a series is given, with one/two term
missing. Choose the correct alternative from the given ones that
will complete the series. [2019 - II]
13. 14, 19, 29, 49, 89,  ?
(a) 1 39 (b) 1 49
(c) 1 59 (d) 1 69
14. 5, 21, 69, 213, 645,     ?   .
(a) 1670 (b) 1941
(c) 720 (d) 1320
15. Fill the blank in the middle of the series or end of the series.
DEF , DEF
2
, DE
2
F
2
, _____, D
2
E
2
F
3
                       [2020 - II]
(a) DEF
3
(b) D
3
EF
3
(c)D
2
E
3
F (d) D
2
E
2
F
2
Series/
Coding-Decoding
2
Page 2


Series/Coding-Decoding C-13
1. Which number comes next in this series ? [2011-II]
1 4 7 10 13 16
(a) 17 (b) 1 9
(c) 21 (d) None of these
2. Which number comes next in this series ? [2011-II]
0 1 3 6 10 15
(a) 19 (b) 2 1
(c) 26 (d) 3 2
3. Look at the series 36, 34, 30, 28, 24, ..... what number should
come next ? [2011-II]
(a) 20 (b) 2 2
(c) 23 (d) 2 6
4. Look at the series 22, 21, 23, 22, 24, 23 ..... what number
should come next ? [2011-II]
(a) 22 (b) 24
(c) 25 (d) 26
5. Look at the series 53, 53, 40, 40, 27, 27 ..... what number
should come next ? [2011-II]
(a) 12 (b) 14
(c) 27 (d) 53
6. Look at the series 8, 22, 8, 28, 8 ..... what number should
come next ? [2011-II]
(a)9 (b) 3 4
(c) 29 (d) 3 2
7. Look at the series 31, 29, 24, 22, 17 ..... what number should
come next ? [2011-II]
(a) 15 (b) 1 4
(c) 13 (d) 1 2
DIRECTIONS (Qs. 8 – 10) : Complete the series [2014-I]
8. A, B, D, G , ?,  P
(a)I (b) J
(c)K (d) L
9. Z , S , W , O , T, K, Q, G , ?, ?
(a) N, D (b) N, C
(c) O, C (d) O, D
10. BCD , RQP , LMN, TS?
(a)U (b) V
(c)R (d) T
11. If A = C , B = D , C = E and so on, code the following:
‘STUDENT’ [2014-I]
(a) VW VF GP V
(b) UUWFGPV
(c) U VWFGPV
(d) U VVF GPV
12. If A = Z, B = Y and so on, code the following: [2014-I]
‘EDITOR’
(a) VWR GLI (b) VW R G VI
(c) VW VG LI (d) V WR LL I
DIRECTIONS (Qs. 13-14) :  a series is given, with one/two term
missing. Choose the correct alternative from the given ones that
will complete the series. [2019 - II]
13. 14, 19, 29, 49, 89,  ?
(a) 1 39 (b) 1 49
(c) 1 59 (d) 1 69
14. 5, 21, 69, 213, 645,     ?   .
(a) 1670 (b) 1941
(c) 720 (d) 1320
15. Fill the blank in the middle of the series or end of the series.
DEF , DEF
2
, DE
2
F
2
, _____, D
2
E
2
F
3
                       [2020 - II]
(a) DEF
3
(b) D
3
EF
3
(c)D
2
E
3
F (d) D
2
E
2
F
2
Series/
Coding-Decoding
2
Series/Coding-Decoding
1. (b)
+3 +3 +3 +3 +3 +3
4 7 10 13 16 19 1
2. (b)
+1
0 3
+2 +3 +4 +5 +6
10 21. 1 6 15
3. (b)
–2
36 30
–4 –2 –4 –2
24 34 28 22
4. (c)
–1
22 23
+2 –1 +2 –1
24 21 22 23
+2
25
5. (b)
53,55
–13
40,40
–13
27, 27
–13
14
6. (b) 8   28, 8,
+6
34 22, 8,
+6
7. (a)
–2
31 24
–5 –2 –5 –5
17 29 22 17
–2
15
8. (c)
A, D, B, G, K ,
+1 +3 +2 +4 +5
P
9. (b)
S O K G C Z W T Q N
–3 –3 –3 –3
–4 –4 –4 –4
10. (c)
B C D
+1 +1
,
R L Q M P N
+1 +1 +1 +1
, , T S R
+1 +1
11. (c)
S T U DE NT
U V W F G PV
¯¯ ¯ ¯ ¯¯¯
ANSWERS & EXPLANATIONS
12. (a)
E D I T OR
V W R G LI
¯ ¯ ¯¯¯ ¯
13. (d) The pattern is as follows :
14       19       29        49       89      169
+5       +10     +20     +40     +80
+5       +10     +20     +40
+5       +10     +20
+5       +10
+5
So, 169 will complete the series.
14. (b) The pattern is as follows :
21 – 5 = 16 Þ 16 × 3 = 48
69 – 21 = 48 Þ 48 × 3 = 144
213 – 69 = 144 Þ 144 × 3 Þ 432
645 – 213 Þ 432 Þ 432 × 3 = 1296
and
1941 – 645 = 1296
15. (d) In this series, the letters remain the same: DEF.
The subscript numbers follow this series:
111, 112, 122, 222, 223, 233, 333, ...