There could be multiple answers to this. RACISM is one such word starting with R and ending with M.
One four letter word that starts with r is riot.
a 4 letter word that begins with r is rice
MIRROR is a six letter word with three r's in it
The first 'r' is silent.February
preserve
A six letter word for a bird of prey starting with the letter R is "raptor."
Three is a multiple of 3.
The letter R is the 4th letter in "attraction."
what is the silent letter for sword
there
or