need-necessary
in Spain we use the word "necessary" all the time, however, I seem to notice native people don´t.
how would you express the following

do I have to write my name here ?

no, it is not necessary.

could "need " replace it ? no, there is no need

when to use "need" and when "necessity"?

thanks

Question

need-necessary
in Spain we use the word "necessary" all the time, however, I seem to notice native people don´t.
how would you express the following

do I have  to write my name here ?

no, it is not necessary.

could "need " replace it ?  no, there is no need

when to use "need" and when "necessity"?

thanks

Answer

This can be confusing.

"Need" can be either a noun or a verb.
"Necessary" is an adjective.
"Necessity" is a noun and it is used much less frequently.

You could write any of these:
No, it is not necessary.
No, it is not needed.
No, it is unnecessary.

Or OK but less common.
No, it is unneeded.
No, there is no need.
No, it's not a necessity.

Answer

no, it is not necessary.

You can write or say,   "No;  it is not needed." or  "No, it is  unnecessary."