IBEW Aptitude Number Series Question and Answers 2 — Questions and Answers
Question 1: What is the next number in the series: 3, 6, 12, 24, 48, ___?
- 72
- 96 (Correct answer)
- 84
- 60
Correct answer: 96
Each term is multiplied by 2: 3×2=6, 6×2=12, 12×2=24, 24×2=48, 48×2=96.
This is a geometric sequence with a common ratio of 2. Each term doubles the previous one. Starting from 3: 3, 6, 12, 24, 48, and the next term is 48 × 2 = 96. Geometric sequences appear frequently on the IBEW NJATC aptitude test.
Question 2: Find the missing number: 100, 91, 83, 76, 70, ___
- 64
- 65 (Correct answer)
- 66
- 67
Correct answer: 65
The differences are -9, -8, -7, -6, -5. Each step the subtracted amount decreases by 1. 70 - 5 = 65.
This is a series with decreasing differences: 100-91=9, 91-83=8, 83-76=7, 76-70=6, so the next difference is 5. Therefore 70 - 5 = 65. Recognizing patterns in differences is a key skill for number series questions.
Question 3: What comes next: 2, 5, 10, 17, 26, ___?
- 35
- 36
- 37 (Correct answer)
- 38
Correct answer: 37
The differences are 3, 5, 7, 9 — odd numbers increasing by 2. The next difference is 11, so 26 + 11 = 37.
The differences between consecutive terms are 3, 5, 7, 9 — an arithmetic sequence of odd numbers. The next difference should be 11, giving 26 + 11 = 37. This type of second-order pattern is common on aptitude tests.
Question 4: Identify the next term: 1, 1, 2, 3, 5, 8, 13, ___
- 18
- 19
- 20
- 21 (Correct answer)
Correct answer: 21
This is the Fibonacci sequence: each term is the sum of the two preceding terms. 8 + 13 = 21.
The Fibonacci sequence adds the two previous numbers to get the next: 1+1=2, 1+2=3, 2+3=5, 3+5=8, 5+8=13, and 8+13=21. This famous sequence appears in aptitude tests to test your ability to recognize non-obvious patterns.
Question 5: What is the missing value: 81, 27, 9, 3, ___?
- 0
- 1 (Correct answer)
- 2
- 3
Correct answer: 1
Each term is divided by 3: 81÷3=27, 27÷3=9, 9÷3=3, 3÷3=1.
This geometric sequence has a common ratio of 1/3 (dividing by 3 each time): 81, 27, 9, 3, 1. Recognizing that you divide by a constant is the key insight. The answer is 1.
Question 6: Find the next number: 5, 10, 20, 40, 80, ___
- 120
- 140
- 160 (Correct answer)
- 180
Correct answer: 160
Each term doubles: 5×2=10, 10×2=20, 20×2=40, 40×2=80, 80×2=160.
This is a geometric sequence with common ratio 2. Each term is multiplied by 2 to get the next. After 80, the next term is 80 × 2 = 160. Doubling sequences are among the most common patterns on IBEW aptitude tests.
IBEW Aptitude Number Series Question and Answers 2
What is the next number in the series: 3, 6, 12, 24, 48, ___?