Question 1

Find the missing term in the series: 3, 4, 7, 13, 24, 44, ?

Accepted Answer

Step 1: Find differences between consecutive terms: 4-3=1, 7-4=3, 13-7=6, 24-13=11, 44-24=20. Step 2: Find second-level differences (differences of differences): 3-1=2, 6-3=3, 11-6=5, 20-11=9. Step 3: Find third-level differences: 3-2=1, 5-3=2, 9-5=4 — these are doubling (1, 2, 4). Step 4: Next third-level difference = 8, so next second-level difference = 9+8=17, next first-level difference = 20+17=37. Step 5: Missing term = 44+37 = 81.

Question 2

What is the next term in the series: 5, 10, 20, 40, 80, ?

Accepted Answer

This is a geometric progression where each term is multiplied by 2. Starting with 5, we have: 5×2=10, 10×2=20, 20×2=40, 40×2=80, 80×2=160.

Question 3

Complete the series: 1, 1, 2, 3, 5, 8, 13, ?

Accepted Answer

This is the Fibonacci sequence where each term is the sum of the two preceding terms. The pattern is: 1+1=2, 1+2=3, 2+3=5, 3+5=8, 5+8=13, 8+13=21.

Question 4

Find the missing number: 2, 3, 5, 7, 11, 13, ?

Accepted Answer

This series contains prime numbers in order. The sequence is: 2, 3, 5, 7, 11, 13, and the next prime number is 17.

Question 5

Complete the series: 3, 6, 12, 24, 48, ?

Accepted Answer

This is a geometric series where each term is multiplied by 2. The pattern is: 3×2=6, 6×2=12, 12×2=24, 24×2=48, 48×2=96.

Question 6

Find the missing term in the series: 2, 5, 10, 17, 26, ?

Accepted Answer

This is a series where each term increases by consecutive odd numbers. The differences are: 5-2=3, 10-5=5, 17-10=7, 26-17=9. The next difference should be 11, so 26+11=37.

Question 7

What comes next in the series: 5, 10, 8, 13, 11, 16, ?

Accepted Answer

This is an alternating series with two interlaced patterns. Odd positions (5, 8, 11, ?) increase by 3. Even positions (10, 13, 16, ?) also increase by 3. The next term is at an odd position, so 11+3=14.

Question 8

What comes next in the series: 1, 4, 9, 16, 25, ?

Accepted Answer

This series consists of perfect squares: 1², 2², 3², 4², 5², ?. The next term is 6² = 36.

Question 9

Find the missing term in the series: 2, 5, 8, 11, 14, ?

Accepted Answer

This is a simple arithmetic progression where each term increases by 3. The pattern is: first term = 2, common difference = 3. So the next term = 14 + 3 = 17.

Question 10

Find the missing term: 2, 5, 10, 17, 26, ?

Accepted Answer

This series follows the pattern where differences between consecutive terms increase by 2 each time. Differences: 3, 5, 7, 9, 11. So 26 + 11 = 37.

Question 11

What comes next? 1, 4, 9, 16, 25, 36, 49, ?

Accepted Answer

This is a series of perfect squares: 1², 2², 3², 4², 5², 6², 7², 8². The next term is 8² = 64.

Question 12

Find the missing number: 5, 11, 23, 47, 95, ?

Accepted Answer

Each term is obtained by multiplying the previous term by 2 and then adding 1. 5×2+1=11, 11×2+1=23, 23×2+1=47, 47×2+1=95, 95×2+1=191. The missing term is 191.

Question 13

Find the missing term in the series: 3, 6, 12, 24, 48, ?, 192

Accepted Answer

This is a geometric series where each term is multiplied by 2 to get the next term. 3 × 2 = 6, 6 × 2 = 12, 12 × 2 = 24, 24 × 2 = 48, 48 × 2 = 96, 96 × 2 = 192. The missing term is 96.

Question 14

Find the missing term: 5, 7, 11, 19, 35, ?

Accepted Answer

This series follows the pattern where each term is obtained by doubling the previous term and subtracting 3. (5×2)-3=7, (7×2)-3=11, (11×2)-3=19, (19×2)-3=35, (35×2)-3=67.

Question 15

Find the missing term: 4, 9, 16, 25, 36, 49, ?

Accepted Answer

This series consists of perfect squares: 2², 3², 4², 5², 6², 7², 8². The next term is 8² = 64.

Question 16

Find the missing term: 1, 1, 2, 3, 5, 8, 13, ?

Accepted Answer

This is the Fibonacci sequence where each term is the sum of the two preceding terms. 8 + 13 = 21.

Question 17

Find the missing term in the series: 3, 6, 12, 24, 48, ?

Accepted Answer

This is a geometric series where each term is multiplied by 2 to get the next term. 3 × 2 = 6, 6 × 2 = 12, 12 × 2 = 24, 24 × 2 = 48, 48 × 2 = 96.

Question 18

Complete the series: 7, 14, 28, 56, 112, ?, 448

Accepted Answer

This is a geometric series where each term is multiplied by 2. 7×2=14, 14×2=28, 28×2=56, 56×2=112, 112×2=224, 224×2=448. The missing term is 224.

Question 19

Study the series: 2, 5, 11, 23, 47, 95, ?, 383

What should replace the question mark?

Accepted Answer

Each term is double the previous term plus an alternating increment. More precisely: differences are 3, 6, 12, 24, 48, ?, 288. The differences double each time (×2). Missing difference is 96, so the missing term is 95 + 96 = 191.

Question 20

Study the series: 5, 6, 8, 11, 15, 20, 26, ?, 41

What should replace the question mark?

Accepted Answer

First differences: 1, 2, 3, 4, 5, 6, ?, 15. The first differences increase by 1 each time. Missing first difference is 7, so the missing term is 26 + 7 = 33.

Question 21

Study the series: 3, 7, 16, 35, 74, 153, ?, 631

What should replace the question mark?

Accepted Answer

Each term is approximately double the previous plus an increment. More precisely: differences are 4, 9, 19, 39, 79, ?, 478. Second differences: 5, 10, 20, 40, ?, 399. The second differences double each time (×2). Missing second difference is 80, so missing first difference is 79 + 80 = 159. Missing term is 153 + 159 = 312.

SSC CHSL Series Completion

SSC CHSL Series Completion — Past Exam Questions

Series Completion— Rules & Concept

Key Points to Remember

Exam-Specific Tips

Series Completion — Practice Questions

60-Second Revision — Series Completion