Alternating and interleaved number series
Lesson 6 of 20 in Union Aptitude Prep. The start plays free here.
- A row of numbers → What comes next?
- Look for a pattern
- 110 → 112 → 107 → 109 → 104
- Gaps: +2, −5, +2, −5
- Alternate positions: 110, 107, 104 | 112, 109, 106
- (−1)¹ = −1; (−1)² = +1
- (−1)³ = −1; (−1)⁴ = +1
- Number series trainer
- Algebra & functions with worked steps
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How the lesson starts
You may see a row of numbers in Algebra and Functions. The question asks what comes next. You look for a pattern to find the answer.
Your sample row reads 110, 112, 107, 109, 104. Adding two works for the first move, but not the second.
Then, in the full lesson
- Taking turns
- Separate the tracks
- Signs take turns
- Follow the sign
- 2 questions along the way
A question from this lesson
Continue the same pattern: 110, 112, 107, 109, 104, 106. What comes next?
- 103
- 108
- 101
Show the answer
C. 101. 101 follows by subtracting five from 106. The rules take turns. 108 repeats adding two. 103 subtracts three from the adjacent number instead of following a separate track.
The full class, $39 once.
Paid once, no subscription. Ask for a refund within 7 days of buying if you’ve done less than 25% of the class.
- Number series trainer
- Algebra & functions with worked steps
- Reading comprehension sets
Not affiliated with IBEW, NECA, ETA or any JATC. Original practice questions only.