I'm not native, but I've heard it pronounced by several different native speakers and it seems to vary based on region.
I've heard all three of the following, in descending order of frequency:
- «Cinco por siete es treinta y cinco»
- «Cinco por siete son treinta y cinco»
- «Cinco por siete es igual a treinta y cinco»
None of these should be particularly surprising as we do the same thing in English.
- "Five times seven equals 35"
- "Five times seven is 35"
- "Five times seven are 35" (I personally find this one inaccurate, but nevertheless there are some speakers who use it)
- "Five times seven is equal to 35"
Something else you might try is going to Youtube and searching for «tablas de multiplicar». That should yield some videos aimed at children with native speakers pronouncing it.
Very helpful, Mikey. My Spanish teacher here in Ecuador said yesterday that multiplication sentences were translated as , "número más número." That didn't make any sense, but I remembered that DL had this multiplication sentence. So, this morning, I reviewed Numbers and found it. I'm with you about "son," but I'll ask native speakers I know here. Thanks too for the idea about tablas de multiplicar. I would be surprised if there aren't mucho videos.
Wow, the discussion here is giving me flashbacks to this song: http://www.youtube.com/watch?v=U9H_KLaDMfs&t=0m52s