You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "reason for getting national insurance number in uk?" whose answer is work in the UK.
Each document should contain about 30 words, and these documents should contain useful information.

Query: primary reasons for getting a national insurance number in uk
Useful Output:

Doc 1: The primary purpose of National Insurance is to create a pool of funds UK workers can access after they become eligible for State Pension. As
Doc 2: Generally, anyone who wants to work in the UK needs a National Insurance number. Employees begin contributing once they start earning over £184
Doc 3: National Insurance Numbers are issued usually when a person turns 16. This number is used to identify a person when being taxed, being paid, and
Doc 4: The NIN is a unique alphanumeric code assigned to individuals in the UK. It serves as a means of identifying you for various purposes related to the country's
Doc 5: a) To record a person's NI contributions and credited contributions; b) As a reference number for the whole social security system. NI contributions are