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Patterns - Number Patterns

Grade 3ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

A Number Pattern is a sequence of numbers that follow a specific rule to find the next number in the series. Imagine a set of stairs where each step is the same height; this represents a consistent increase in value.

The Rule of a pattern is the logical link that tells us how to get from one number to the next. To identify it, we look at the difference between two consecutive numbers. If the numbers are growing, we look for addition; if they are shrinking, we look for subtraction.

Increasing Patterns occur when each term is larger than the previous one, usually by adding a fixed number. For example, in 4,8,12,164, 8, 12, 16, the rule is to add 44. Visually, this looks like a bar graph where each bar is taller than the one to its left by an equal amount.

Decreasing Patterns occur when each term is smaller than the previous one, usually by subtracting a fixed number. In the sequence 50,45,40,3550, 45, 40, 35, the rule is to subtract 55. This can be visualized as a countdown or a set of blocks being removed one by one.

Skip Counting is a pattern where we count by jumping over numbers by a fixed interval, such as 2s,5s,10s,2s, 5s, 10s, or 100s100s. On a number line, this is represented by equal-sized 'hops' from one number to the next.

Even and Odd Patterns follow specific sequences. Even numbers always end in 0,2,4,6,0, 2, 4, 6, or 88 and follow the pattern +2+2. Odd numbers end in 1,3,5,7,1, 3, 5, 7, or 99 and also follow a +2+2 pattern but start from an odd digit. Even numbers can be visualized as pairs of dots with no single dot left alone.

Repeating vs. Growing Patterns: A repeating pattern has a core sequence that stays the same (e.g., 1,0,1,01, 0, 1, 0). A growing pattern changes in a predictable way (e.g., 1,11,1111, 11, 111). A repeating pattern looks like a decorative border on a wall, while a growing pattern looks like a pyramid being built layer by layer.

📐Formulae

Rule for Addition: Next Term=Current Term+Difference\text{Rule for Addition: } \text{Next Term} = \text{Current Term} + \text{Difference}

Rule for Subtraction: Next Term=Current TermDifference\text{Rule for Subtraction: } \text{Next Term} = \text{Current Term} - \text{Difference}

Finding the Difference: Term2Term1=Difference\text{Finding the Difference: } \text{Term}_2 - \text{Term}_1 = \text{Difference}

Even Numbers={2,4,6,8,}\text{Even Numbers} = \{2, 4, 6, 8, \dots\}

Odd Numbers={1,3,5,7,}\text{Odd Numbers} = \{1, 3, 5, 7, \dots\}

💡Examples

Problem 1:

Identify the rule and find the next two numbers in the pattern: 24,28,32,36,24, 28, 32, 36, \dots

Solution:

Step 1: Find the difference between the first two numbers: 2824=428 - 24 = 4. \nStep 2: Check the next pair: 3228=432 - 28 = 4. \nStep 3: The rule is 'Add 44'. \nStep 4: Find the next number: 36+4=4036 + 4 = 40. \nStep 5: Find the following number: 40+4=4440 + 4 = 44. \nFinal Pattern: 24,28,32,36,40,4424, 28, 32, 36, 40, 44.

Explanation:

Since the numbers are increasing, we use subtraction to find the gap between them, which determines the constant addition rule.

Problem 2:

Complete the decreasing pattern: 95,85,75,,55,95, 85, 75, \dots, 55, \dots

Solution:

Step 1: Find the difference: 9585=1095 - 85 = 10. \nStep 2: Confirm with the next pair: 8575=1085 - 75 = 10. \nStep 3: The rule is 'Subtract 1010'. \nStep 4: Find the first missing number: 7510=6575 - 10 = 65. \nStep 5: Verify the next number: 6510=5565 - 10 = 55 (given). \nStep 6: Find the last missing number: 5510=4555 - 10 = 45.

Explanation:

This is a skip-counting pattern in reverse (counting backwards by 10s10s). We subtract the common difference from the preceding number to fill the gaps.