Let's solve each number sequence and find the rule for each one. We'll analyze the pattern step by step.
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1. Sequence: 6, 9, 12, 15, 18, 21
Step-by-step analysis:
- 9 - 6 = 3
- 12 - 9 = 3
- 15 - 12 = 3
- 18 - 15 = 3
- 21 - 18 = 3
✔ The numbers increase by
3 each time.
Rule: Add 3 to the previous term.
Or in formula form:
aₙ = 6 + (n - 1) × 3, where n is the position in the sequence.
👉
Answer: *Add 3 each time.*
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2. Sequence: 3, 9, 27, 81, 243, 729
Step-by-step analysis:
- 9 ÷ 3 = 3
- 27 ÷ 9 = 3
- 81 ÷ 27 = 3
- 243 ÷ 81 = 3
- 729 ÷ 243 = 3
✔ Each term is multiplied by
3.
This is a geometric sequence with common ratio 3.
Note:
- 3¹ = 3
- 3² = 9
- 3³ = 27
- 3⁴ = 81
- etc.
So the nth term is
3ⁿ.
👉
Answer: *Multiply by 3 each time.*
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3. Sequence: 42, 40, 38, 36, 34, 32
Step-by-step analysis:
- 40 - 42 = -2
- 38 - 40 = -2
- 36 - 38 = -2
- 34 - 36 = -2
- 32 - 34 = -2
✔ Decreases by
2 each time.
Rule: Subtract 2 from the previous term.
👉
Answer: *Subtract 2 each time.*
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4. Sequence: 14, 20, 26, 32, 38, 44
Step-by-step analysis:
- 20 - 14 = 6
- 26 - 20 = 6
- 32 - 26 = 6
- 38 - 32 = 6
- 44 - 38 = 6
✔ Increases by
6 each time.
Rule: Add 6 to the previous term.
👉
Answer: *Add 6 each time.*
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5. Sequence: 2, 6, 18, 54, 162, 486
Step-by-step analysis:
- 6 ÷ 2 = 3
- 18 ÷ 6 = 3
- 54 ÷ 18 = 3
- 162 ÷ 54 = 3
- 486 ÷ 162 = 3
✔ Each term is multiplied by
3.
Geometric sequence with ratio 3.
First term = 2 → 2 × 3^(n-1)
👉
Answer: *Multiply by 3 each time.*
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6. Sequence: 47, 42, 37, 32, 27, 22
Step-by-step analysis:
- 42 - 47 = -5
- 37 - 42 = -5
- 32 - 37 = -5
- 27 - 32 = -5
- 22 - 27 = -5
✔ Decreases by
5 each time.
Rule: Subtract 5 from the previous term.
👉
Answer: *Subtract 5 each time.*
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✔ Final Answers:
1.
Add 3 each time.
2.
Multiply by 3 each time.
3.
Subtract 2 each time.
4.
Add 6 each time.
5.
Multiply by 3 each time.
6.
Subtract 5 each time.
These are all arithmetic or geometric sequences with consistent rules. Let me know if you'd like them written in formula form!
Parent Tip: Review the logic above to help your child master the concept of pattern rule worksheet grade 4.