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Class 4 Maths Adventure

Number Patterns

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🔵Growing Patterns

A pattern is a sequence that follows a rule. In a growing pattern, each term is larger than the one before it.

  • Add patterns: 5, 10, 15, 20, 25 — Rule: +5 each time
  • Multiply patterns: 2, 4, 8, 16, 32 — Rule: ×2 each time

To find the rule: check what you add or multiply to get from one term to the next. Then use that rule to find the missing term.

Steps to extend a growing pattern:

  1. Look at two consecutive terms
  2. Find the difference (for add) or ratio (for multiply)
  3. Check it works for the next pair too
  4. Apply the rule to find the next term
Growing Patterns2481632x2x2x2x2Rule: x2 (multiply by 2 each time)
👀 See a worked example
Find the next two terms: 3, 6, 9, 12, ___, ___ Step 1: 6 - 3 = 3, 9 - 6 = 3, 12 - 9 = 3. Rule = +3 each time. Step 2: 12 + 3 = 15. Step 3: 15 + 3 = 18. Answer: 15, 18
What is the missing term? 1, 2, 4, 8, ___, 32 Step 1: 2 ÷ 1 = 2, 4 ÷ 2 = 2, 8 ÷ 4 = 2. Rule = ×2 each time. Step 2: 8 × 2 = 16. Step 3: Check: 16 × 2 = 32. Answer: 16
A pattern starts at 5 and adds 7 each time. Write the first 5 terms. Term 1: 5. Term 2: 5 + 7 = 12. Term 3: 12 + 7 = 19. Term 4: 19 + 7 = 26. Term 5: 26 + 7 = 33. Pattern: 5, 12, 19, 26, 33

🤖 Vidi's Key Points

  • A growing pattern gets larger with each term
  • Add patterns: find the difference between consecutive terms
  • Multiply patterns: find what you multiply each term by
  • Always check your rule works for at least two pairs of terms

🟢Shrinking Patterns

In a shrinking pattern, each term is smaller than the one before it. The sequence is going down.

  • Subtract patterns: 40, 35, 30, 25 — Rule: -5 each time
  • Divide patterns: 64, 32, 16, 8 — Rule: ÷2 each time

Some patterns have a changing difference — this makes them trickier.

Example: 55, 50, 44, 37, 29 — differences are -5, -6, -7, -8 — so the next difference is -9, making the next term 29 - 9 = 20.

Always check if the difference is constant (same) or changing (increasing or decreasing).

Shrinking Pattern: 64, 32, 16, 8, 464321684÷2÷2÷2÷2Rule: ÷2 (divide by 2 each time)
👀 See a worked example
Find the next term: 100, 90, 80, 70, ___ Step 1: 100 - 90 = 10, 90 - 80 = 10, 80 - 70 = 10. Rule = -10 each time. Step 2: 70 - 10 = 60. Answer: 60
Find the next term: 81, 27, 9, 3, ___ Step 1: 81 ÷ 27 = 3, 27 ÷ 9 = 3, 9 ÷ 3 = 3. Rule = ÷3 each time. Step 2: 3 ÷ 3 = 1. Answer: 1
Find the next term: 55, 50, 44, 37, 29, ___ Step 1: differences are 55-50=5, 50-44=6, 44-37=7, 37-29=8. The differences increase by 1 each time. Step 2: next difference = 9. Step 3: 29 - 9 = 20. Answer: 20

🤖 Vidi's Key Points

  • A shrinking pattern gets smaller with each term
  • Subtract patterns: find the constant difference being subtracted
  • Divide patterns: find what you divide each term by
  • Some patterns have a changing difference — check if the gap increases or decreases

🟣Input-Output Tables and Rules

An input-output table shows pairs of numbers connected by a rule — like a machine that transforms the input into the output.

The rule can be:

  • Add or subtract: Input 3 → Output 8 (Rule: +5)
  • Multiply or divide: Input 4 → Output 12 (Rule: ×3)
  • Two-step rule: Input 2 → Output 5 (Rule: ×2+1)

How to find the rule:

  1. Look at the first input-output pair
  2. Try simple operations (+, -, ×, ÷)
  3. Test your rule on at least two more pairs
  4. If it works for all pairs, you have the rule

Once you know the rule, you can find any output for any input.

Input-Output Table (Rule: x3)InputOutputRule: x 31, 2, 3, 4, 53, 6, 9, 12, 15Input x 3 = Output4 x 3 = 12 check, 5 x 3 = 15 check
👀 See a worked example
Find the rule: Input 5 → 15, Input 8 → 24, Input 10 → 30. What is the output when input = 6? Step 1: Try ×3: 5×3=15 (yes!), 8×3=24 (yes!), 10×3=30 (yes!). Rule = ×3. Step 2: When input=6, output = 6×3 = 18. Answer: 18
Find the rule: Input 2 → 5, Input 3 → 7, Input 4 → 9. What is the output when input = 10? Step 1: Try ×2+1: 2×2+1=5 (yes!), 3×2+1=7 (yes!), 4×2+1=9 (yes!). Rule = ×2+1. Step 2: When input=10, output = 10×2+1 = 21. Answer: 21
Input 1→1, 2→4, 3→9, 4→16. What is the rule and the next output? Step 1: Notice 1=1×1, 4=2×2, 9=3×3, 16=4×4. Rule = input × itself (square the number). Step 2: Next input=5. Output = 5×5 = 25. Answer: 25

🤖 Vidi's Key Points

  • An input-output table shows how inputs are transformed by a rule
  • Test your rule on ALL given pairs before finalising it
  • Rules can be one-step (x3) or two-step (x2+1)
  • Squaring means multiplying a number by itself: 4x4=16

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