Our main objective in this note is to prove the following. Suppose R is a
ring having an idempotent element e(e≠0, e≠1) which satisfies:
(M1) xR=0 implies x=0.(M2) eRx=0 implies x=0 (and hence Rx=0 implies x=0).(M3) exeR(1−e)=0 implies exe=0.
If d is any multiplicative derivation of R, then d is additive.