IBEW Number Sequence Questions — How to Find the Pattern Every Time
Number sequences look intimidating until you learn the three patterns that cover almost every question. After working through these examples, you'll spot the pattern in under 10 seconds.
The Three Types of Sequences
- Arithmetic — add or subtract the same number each step.
- Geometric — multiply or divide by the same number each step.
- Mixed — the differences themselves form a pattern.
The 3-Step Method
- Are the differences constant? It’s arithmetic.
- Is each term a constant multiple of the previous? It’s geometric.
- Look at the differences. If they form a pattern, use it.
10 Practice Sequences
1. 4, 8, 16, 32, ___
Pattern: ×2 each step. Answer: 64.
2. 144, 121, 100, 81, ___
Pattern: perfect squares descending. 12², 11², 10², 9², 8². Answer: 64.
3. 2, 5, 10, 17, 26, ___
Pattern: differences are 3, 5, 7, 9 — odd numbers. Next +11. Answer: 37.
4. 1, 4, 9, 16, 25, ___
Pattern: perfect squares. Answer: 36.
5. 100, 50, 25, 12.5, ___
Pattern: ÷ 2 each step. Answer: 6.25.
6. 3, 6, 12, 24, ___
Pattern: ×2. Answer: 48.
7. 1, 1, 2, 3, 5, 8, ___
Pattern: Fibonacci — each term is the sum of the two before it. Answer: 13.
8. 7, 14, 21, 28, ___
Pattern: +7 (arithmetic). Answer: 35.
9. 90, 81, 72, 63, ___
Pattern: −9 (arithmetic). Answer: 54.
10. 3, 7, 13, 21, 31, ___
Pattern: differences are 4, 6, 8, 10 — increasing by 2. Next +12. Answer: 43.
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Take the Free Practice TestFrequently Asked Questions
What types of number sequences are on the IBEW aptitude test?
Three main types: arithmetic (add/subtract the same number each step), geometric (multiply/divide the same number each step), and mixed sequences where the differences themselves form a pattern.
How do I find the pattern in a number sequence?
First check if you add the same number each step (arithmetic). If not, check if you multiply by the same factor (geometric). If neither, look at the differences between consecutive terms — they often form their own pattern.
Are number sequences hard on the IBEW aptitude test?
Most applicants find them moderate. The trick is pattern recognition. After working through 20-30 practice sequences, the patterns become predictable.
Related Resources
Michael B.
IBEW Local 134 Journeyman Electrician · Licensed Electrical Contractor
Michael is an IBEW Local 134 journeyman and licensed electrical contractor. He teaches federal pre-apprenticeship on the south side of Chicago, helping students get into the IBEW. He built this practice test because he knows exactly what the NJATC aptitude exam tests — and what trips people up. If you prep with this, you walk in ready.