the ending in M of word сопоставлением

Question

"сопоставлением" i want to know why this word is ending in  M.

It is not the first time when i see a word ending in m.The translation of this word  Is "comparison".

Answer 1

It's related to the case of the word. In 1 form comparison is "сопоставлениЕ" without M. It's very coomon, for example, the same situation is with "удивление" (astonishment).

"Это вызвало у меня удивление" (it surprises me) , but "я с удивлением услышал эту новость" (I was surprised to hear this news). 

Comments

i think after what you told me that the first form is for present tense without M and the second form is for past tense with M.i think the second form is what do we call past perfect in english.

Answer 2

this is Творительный подеж (instrumental case); for this word and another finished in ...ние, "сопостовление", always change to   нием