What is the rule for the nth term in the following sequence?9, 15, 21, 27, …

A number sequence involves following a pattern. You have to spot the pattern. For example, in the sequence 8, 16, 32, 64, ... each number in the sequence can be got from the previous term by multiplying by 2. In this case, the rule is: multiply by 2. The numbers in a sequence are called 'terms': in 5, 10, 15, 20, ... '5' is the first term and '15' is the third term. If you want to talk about a term without naming it, you call it the nth term. For example, if n = 3, this is the 3rd term.  Tips: 1. To form a sequence from a given rule for the nth term, put n = 1 first, then n = 2, then n =... Show more

A number sequence involves following a pattern. You have to spot the pattern.

For example, in the sequence 8, 16, 32, 64, ... each number in the sequence can be got from the previous term by multiplying by 2.

In this case, the rule is: multiply by 2. The numbers in a sequence are called 'terms': in 5, 10, 15, 20, ... '5' is the first term and '15' is the third term.

If you want to talk about a term without naming it, you call it the nth term. For example, if n = 3, this is the 3rd term. 

Tips:

1. To form a sequence from a given rule for the nth term, put n = 1 first, then n = 2, then n = 3 and so on - depending on how many terms you are asked to find. If you are asked to find 5 terms, then you will go as far as n = 5.

2. To create a number sequence from a given rule, all you have to do is apply the rule to each number.

For example, if the rule is nth term = 2n, the process to follow would be this:

n = 1 gives 2 × 1 = 2

n = 2 gives 2 × 2 = 4

n = 3 gives 2 × 3 = 6

n = 4 gives 2 × 4 = 8

 

Related Tests:

11 Plus (11+) Maths Practice Test: Number Sequences (Very Easy)

11 Plus (11+) Maths Practice Test: Number Sequences (Easy)

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