Block address from word address

I'm working a homework problem that asks me the following.
using the series of references 1,4,8,5,20,17,19,56,9,11,4,43,5,6,9,17, show the hits and misses and final cache contents for a two-way set associative cache with one-word blocks and a total size of 16 words. Assume LRU.

I know what the majority of the question is asking me, but I have a problem with one aspect. I have searched online for the answer and found only the following.

Block address = ( byte address ) / (bytes per block)

the series of references are word addresses and i'm supposed to find the block address so i can find the word address.

in dmc i would just divide the word address by the # of blocks.
ie.
4 word block with 16 words for the cache
4 blocks total in the cache
1/4 = 0
4/4 = 1
etc.

but when you have 2-way associativity what is the block number you use?
would i use the number of blocks in the set or the number of blocks in the cache total?
would i divide by 2 or by 16?

thank you for any help.