๐งฉ Number Patterns
A growing pattern gets larger with each term
โถ Play Door 17Growing Patterns
A pattern is a sequence that follows a rule. In a growing pattern, each term is larger than the one before it.
โข Add patterns: 5, 10, 15, 20, 25 โ Rule: +5 each time
โข Multiply patterns: 2, 4, 8, 16, 32 โ Rule: ร2 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:
โข Look at two consecutive terms
โข Find the difference (for add) or ratio (for multiply)
โข Check it works for the next pair too
โข Apply the rule to find the next term
Worked example
Problem: 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
Shrinking Patterns
In a shrinking pattern, each term is smaller than the one before it. The sequence is going down.
โข Subtract patterns: 40, 35, 30, 25 โ Rule: -5 each time
โข Divide patterns: 64, 32, 16, 8 โ Rule: รท2 each time
Some patterns have a changing difference โ this makes them trickier.
Example: 55, 50, 44, 37, 29 โ differences are -5, -6, -7, -8 โ 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).
Worked example
Problem: 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
Input-Output Tables and Rules
An input-output table shows pairs of numbers connected by a rule โ like a machine that transforms the input into the output.
The rule can be:
โข Add or subtract: Input 3 โ Output 8 (Rule: +5)
โข Multiply or divide: Input 4 โ Output 12 (Rule: ร3)
โข Two-step rule: Input 2 โ Output 5 (Rule: ร2+1)
How to find the rule:
โข Look at the first input-output pair
โข Try simple operations (+, -, ร, รท)
โข Test your rule on at least two more pairs
โข If it works for all pairs, you have the rule
Once you know the rule, you can find any output for any input.
Worked example
Problem: Find the rule: Input 5 โ 15, Input 8 โ 24, Input 10 โ 30. What is the output when input = 6?
- Step 1: Try ร3: 5ร3=15 (yes!), 8ร3=24 (yes!), 10ร3=30 (yes!).
- Rule = ร3.
- Step 2: When input=6, output = 6ร3 = 18.
Answer: 18