Title DECOMPOSITION OF k(t) AS A SUM OF FINITELY MANY PROPER SUBFIELDS Type Presentation Keywords Field, sum of subfields, rational function field, L¨uroth’s Theorem. Abstract In this note we prove if k(t) is sum of two proper subfields, then for each n ≥ 2 it is an unshortenable sum of n proper subfields which contains k. Researchers Reza Mahmoudi (First researcher)hamidreza dorbidi (Second researcher)Morteza Jafarpour (Third researcher)hasan barsam (Fourth researcher)