Question as in title,
Find the number of common, odd positive divisors of $27, 900$ & $20, 700$.
explaining the steps in your method would be much appreciated.
I prime factorized and got that the common factor is $2^2\cdot3^2\cdot5^2$, then my notes from the relevant lecture simply go on to a solution implied from that step that the number of common odd positive divisors = $(2+1)(2+1)=9$. How the one leads to the other is where I've fallen down.
So how can you tell the number of common, odd positive divisors of $2^2\cdot3^2\cdot5^2$?