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Example 3: Identify the pattern rule in the given number pattern.

20, 25, 30, 35, 40, 45 …

Solution: The numbers in the given number pattern are arranged in an increasing
order. This means we have used either addition or multiplication to form
the series.
Observe that on adding 5 to a number,

we get the next number of the number Mental Maths
pattern. Write the fifth number of the
number pattern:
20 25 30 35 40 45
3, 7, 11, 15, _______.

+5 +5 +5 +5 +5

So, the rule is to start at 20 and add 5 each time.

Example 4: Identify the pattern rule in the given number pattern.
98, 95, 92, 89, 86 …

Solution: The numbers in the given number pattern are arranged in a decreasing order.
This means we have used either subtraction or division to form the number
pattern.

Observe that on subtracting 3 from a number, we get the next number in the
series.
98 95 92 89 86

–3 –3 –3 –3

So, the rule is to start at 98 and subtract 3 each time.

Example 5: Identify the pattern rule in the given number pattern.
2, 4, 8, 16, 32, 64 …

Solution: The numbers are arranged in an increasing order.
In this example, observe that by considering the first two numbers, the rule
can be either add 2 or multiply by 2. However, when we consider the third

number also, we find that it can be obtained only by multiplying by 2.
2 4 8 16 32 64

×2 ×2 ×2 ×2 ×2
So, the rule is to start at 2 and multiply by 2 each time.

Letter Patterns
In a letter pattern, we arrange letters to follow a rule. We can identify the pattern rule by
comparing the first few letters of the letter pattern.

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