Is it spelled necassary or necessary?

It's spelled necessary.

n - e - c - e - s - s - a - r - y

not necasary,

not necasery,

not necassary,

not necassery,

not necesary,

not necassary,

not necassery,

not neccasary,

not neccasery,

not neccassary,

not neccassery,

not neccesary,

not neccassary,

and not neccassery.